I've been consistently finding blocks once per day with my Core 2 Quad 9400 OC'ed to 3.5GHz on the second windows client. My pps is usually around 2500, so I'm either very lucky or something is wrong on your end.
I can attest to you being lucky. I've been running a constant ~2700 PPS for almost 48 hours and haven't found squat.
Running Sieve% 10, SieveSize 1000000