tuniq, i also lapped my cpu too. and in all honisty it wasnt as bad as i thought it would be it didnt take but a hour, and it goes by alot faster if u have a radio
edit: sence it would be a TRUE that you would be lapping i bet you would see a better preformace increase. also check out autozone for sand paper i found a veriety pack of 220, 400, 800, and 1000 for $4, if you want to go higher i went to O'reillys too they had some 1500 but were selling it only in packs and were charging $10 for the pack. id say just check out some auto parts stores and see what they have because thats the only place you will find over 600 grit besides the internet.
Lol i have more sandpaper than i need...and should be a quick sand with my desk top disc sander.