I have a P4 with XP. It is not excellent as the other Celeron 450. You are right. For instance, the P4 one has a turbo-cache vga card that makes me crazy.

I do not know whether you know these. So I spent a little time in writing these:
It may be something else. For instance, use an older card with its latest drivers, if you have. If it is no solution or you do not have an older one, do, before going to service, decreae hardware acceleration of the video card and restart. If you play music while you are on GE and the sound card is onboard, decreasing hardware acceleration of the sound card in directX will help.

But be sceptical because, for instance, my P4 is not available for the GE although the video RAM is 512, the Ram is over 1GB, etc etc. It is fast but not for the GE.