If it has more than 4GB of system memory stick with windows 7, you can make windows 7 look like XP and win 7 can use more than 4GB memory. Xp can only use 3-4GB memory.
XP can only utilize 3 gigs RAM. I have 4 gigs in my box. I’m running XP and have it in classic mode with all the “old fashioned” options turned on so that it looks just like windows 95.