Can I use my Dell Inspiron 4000 for school?

I know it's pretty old but I found it today in my closet and I kinda need a laptop for college. The library is packed sometimes and it's very hard to find a computer (like this week of midterms). I think I stopped using it because it needs to be reformatted, it has some viruses, and it needs a new battery because once I unplug the cord it shuts off. Also, I would need to get a wifi card or stick to use when I'm on campus or at home. I was going to use this until I finished saving up for a Mac, (I have an imac right now and i prefer them over PC's). Does it sound like this computer would cost me too much to put some work into it to use it? Would I be better off just waiting to buy a Macbook?