Best answer as chosen by user bee1177: Ram considerations
Take a quick check to verify what your PC can handle:
Enter your PC info and allow it to answer. The caveat is that while your PC ran Me before, it takes more ram to run newer OSes. Provided your PC can handle it, I suggest XP as the best OS as Vista is too much, plus it may not accept it anyways. You need at least 512mb to run XP well, though 256mb is allowable, but you're not going to be thrilled. Also, understand, whatever ram you currently have could possibility be removed in order to use higher Mb sticks to replace them. So, if you have 2x128mb now, to get 512mb(2x256mb) they have to be history. This all depends on your specs, etc..