So my story is written in word and I'm scared one day the file wont open because it's too big, or wont save, or when it comes time to publish something will be wrong with it being done in word/something unexpected will happen when it's pulled from it.

So what the hell should I be writing in? If it doesn't have an in built spell checker forget it. I don't want fancy shmancy tools for organizing shit (well, chapters might be okay but I'd rather be able to print them all and maybe even one at a time, instead of having to open each one sort of thing, I want this all together) because I do that with my own stuff off the computer. I have portfolios for all my characters, all hand written (I'll show you guys one day!).

So yeah....what should I use instead of Word?

I don't quite understand - probably millions of people use Word (or the free equivalents OpenOffice / LibreOffice) - they all save in multiple formats, all are fairly standardized by now and all have spell check.

Notepad / Wordpad are the only other ones that I know of that will save as simple text files and can handle almost any size, but no spell checkers.

Personally I don't like Word because it messes up my formatting - I use OpenOffice - but that's probably just because of the way I work, plus I don't like to support Microsoft if I don't have to. 

I'd stick with Word, because it is more or less universally acceptable, when you're sending documents to others. When I was doing my two dissertations for my degrees, I was also worried about losing stuff, because  there was two years of research and writing in them. Even though I had never, ever lost a document in Word, I wanted an extra level of security.

What I did - and what may work for you - was to save each chapter as a separate document, to minimise the loss. Also, you could save them on a memory stick, so you have a copy away from the computer, in case you get a situation where you can't recover data. I can't think of anything else you could do.

Yes meticulous (paranoid even) backups are a must! I use open office but I love word 2003... I can make art with that!

I was just worried about the sending a sample into agents or even making it into an eBook or what ever lol. I will use InDesign for an eBook, but I don't know about the other stuff.

As far as I know most ebook publishers gladly accept Word. I second Sandra's thoughts on back-ups and saving each chapter. Heck, auto-save to a thumb drive every minute if you want!

I would avoid notepad because it does not wrap around to the next line.  You would be writing one continuous sentence for all eternity.  I would strictly use that if you have a quick thought in your head that you need to jot down so you don't forget it.

I understand the fear of word or any software when you are a writer.  Your work is akin to your baby and it is hard to not be paranoid or overprotective about it.  I may use a hard notebook to start because I plan to write only on my lunch breaks at work.  Eventually I would transfer to word.

You can make notepad wrap, but it prints very weird.

Don't write at work, they can claim it as theirs because you wrote on the job and they were paying for your time... Will post about this soon .

You can use Google Docs. It's a bit of an unorthodox option, but it works pretty well, actually. It has a spellcheck, it's pretty much like Word, only you have it connected to your Gmail account - so you can write even if you're using somebody else's PC at the moment!
Not everybody likes Google Docs, but I'm a huge fan, personally.

I have extensive user manuals I've written for work in word.  They are 400+ pages long with high quality images and they still open (might take a second, but they do).  If you are that worried about them not opening after a certain size, cut it off at that point.  Have one document that is chapters 1 through 10, another that is 11 through 20, etc.  That said, you shouldn't worry about word not opening a large text document, that is literally what it was built for.

As someone who's worked for publishing houses in the past, a bit of advice:
Unless you know what you're doing, use a .doc document, or something that can be either converted into a .doc file in Word or read by Word. That way the Printers can make the changes they need to on their end. Meticulous backups is standard advice. However, if you do have a bit more technical know-how, you can save space and preserve the integrity of your document if you save in a .pdf format and embed the fonts. This means that no matter how many years pass, any machine that can read .pdf in any way at all should display what you've written exactly the same as on the original machine that you wrote it. It ensures uniformity and reduces the requirements of the local machine.
The main drawback of using .pdf is unless used correctly, it can be more finicky for Printers to edit the file when necessary.
It shouldn't be too much of an issue unless you've royally borked it and any good print house will adjust to the best of their ability and tell you if there's a problem, but not all print houses are good. To avoid getting screwed over, ask to have a 'proof' to approve before they run your job. This is a good idea even if you haven't submitted a .pdf. They'll send you a copy of what they'd print, if you like it you sign off on it and they run that. If you don't, they alter it until you're happy.
(The process for printing even a simple document can easily become very complicated for reasons that frankly, can border on the arcane. And I've seen former superiors of mine spend much time on the phone dealing with irate clients whose final product didn't meet expectations, always ask for a proof.)
Anyway yeah, .pdf's are good for storage and final product but can be screwy to edit. Personally when I've had to do it in the past, I converted it to a different file format first, like an .indd.

I might look up a guide or write something up about some of the things I've covered here at some point but those are some of the basics for people who've no idea.

Continue writing on Word. My suggestion is to constantly save your work. I have a habit of saving my work after every sentence I write down. (An easy way to do so is by holding CTRL + S at the same time). It will automatically save your work.

Word is probably the easiest application to use if you're to be writing online. You can easy edit and rearrange your words quickly.

I'm pretty sure Word has an autosave feature still yeah?

Yes, Word still has an auto-save feature but you may still lose a few sentences here or there if your computer crashes before the most recent save has taken place.

If you're really scared of your document becoming corrupt, I would recommend the approach of "don't put all your eggs in one basket." For example, save each of your book chapters separately and have a backup of those documents on a separate drive. While one of those files may become corrupt, changes are, they won't ALL become corrupt at once.

You could also save different versions of the same overall document. So for example, go ahead and save today's copy under a slightly different name (Book A - 2-23 Save). Your previous version (Book A) will still be saved in its current form and untouched so that if your newer version becomes corrupt, you'll still have an older copy. Save another version in a week, etc. This way, if one does become corrupt, you'll still have a "fairly recent" version to work with instead of losing everything.

I think you will be fine with writing your story in Word; it is the most reliable writing form that I have ever used and there is the great invention of spell check!  I would not dare writing something without spell check either as my fingers go so fast on the keyboard that I make a lot of mistakes.

My word of advice (no pun intended there ) is to get yourself a big flash drive and back up all your work to that; you can even save it by chapter so that, if you lose something, at least it would not be the entire project.  You can get a large capacity flash drive at Office Max for cheap when they are on sale.

Word should work just fine.