You don't need more than 400 dpi for 1280 resolution.
Phoon used to have a "useful DPI calculator" but the site is down - 400 dpi is fine as long as you don't play on more than 1600x1050 res.
WMOs can be bought on ebay and amazon.
Abyssus is an ok mouse if you have the proper mousepad (QCK heavy not being one of them), but some users experience jittering on pretty much any mousepad (old sensor).
I got the MouseMovementRecorder and the awesome MarkC app. Built a custom .reg file aiming for 1:1 mouse precision. I've applied the reg and restarted, tried moving the mouse but MouseMovementRecorder is giving me a red column. EnPtPr is OFF. What im missing on there?