I've been using the same dell dimension 2400 since 2003. its still running great and i put alot of upgrades into it since than but its still a great computer.
i must say i never thought i would have one for this long and not have it smoke or flame up lol
if i was to ever get another computer it would definetly be a dell. i bought it for $400 back than and put about another $500 into it and it works just as good as my mothers new dell she just got.
i have also had a HD problem that wouldnt let me computer start up. i fixed it by getting a Malwear program from my mother that got rid of the virus. its good to have people know what there doing in the family. and just like anything else. see her do it for so many years i picked up on it and can now fix my own computers 90% of the time. i always thought it was a good idea to have 2 HDs just in case one got infected, so i save all the stuff i worried about to a second HD and once its clear i can transfer it over. cost me $25 for a 40Gig HD just for that. havent had a problem ever since
but good luck with the new computer, and if you ever need a copy of windows XP let me know. i got a couple of new copys from my work when they switched all there new computers from vista back to XP