You have one of the faster p4's made. If your board isn't listed on the hp website with supported cpus, then I would contact hp about an upgrade. Your board bios will determine what cpu it will recognize. I used compaq's free online chat to discuss options with my compaq pc, and ended up changing out the motherboard and reinstalling windows using a dell windows dvd. The old p4's above 3.0 ran pretty warm. Fry's had an e5200 with board for only $80 last week that would have fit in your hp case. You'll have to decide for yourself if you're capable of changing out a motherboard and are willing to format the hardrive and start over, or back up your files first before formatting.