I had to ditch my Dell Optiplex GX400 after 15 years due to noisey fan & faulty motherboard. And will never purchase another Dell again. Due to the fact i forgot i had a Dell Win XP O.S. then installed it into my backup desktop mistakenly. Now i have to purchase another XP O.S this time for my Compaq Presario which is a lot quieter than the outgoing Dell. Question is what Win XP O.S. would work on my Compaq Presario AMD Durion. Do i have to purchase a Compaq Win XP or any Standard Win XP O.S.?? P.S. (After the Dell XP O.S. was installed in the Compaq Presario the screen stated the following message 'A disk read error occurred Press Ctrl + Alt+Del to restart'