I have played around with a MS Intellimouse Explorer with the new 33% better crap or whatever. It was on a dull blue generic mousepad and in counterstrike and unreal tournament I skipped whenever I tried to do a real quick move. Messed around with settings and tried the dull, fake wood desk, and it still skipped. Now, granted it wasn't THAT bad, and only happened maybe once every five matches on CS, but still, that's enough to get me killed in that match, and my ball mouse wouldn't have. I'll check into the Logitech USB line, thanks. BTW, I will use an optical for other games and general use, but for FPS it really does skip for me, maybe it's just my playing style of moving so fast.