Hello kcraye.

I understand that you want to upgrade to Windows XP and a Pentium 4 processor. Updating to Windows XP is not hard, its as simple as popping in the CD and runnign the installer. Upgrading to a Pentium 4 processor will be tough. You have to make sure that all your parts are compatible with a Pentium 4 processor. Also, each processor has a specific socket type (ex. 478, 754, 939, etc.) You have to make sure that you get a Pentium 4 or similar processor that will fit into your motherboard's socket correctly.