If it helps any, these are my stats, though i just started watercooling 2 days ago.
Rig:
AMD XP1700b+ @ 2.2GHz (1.71v actual MBM5)
GeForce 4 Ti4200 (not o/c'd)
eheim 1250 -> dtek pro core -> white water -> maze4 gpu -> eheim 1250 (in series)
Idle:
room temp - 81.6F (27.5C) digital thermometer
CPU temp - 116F (46.6C) MBM5 / 107.4F (41.8C) probe behind mobo
GPU - 102F (38.8C) probe behind card
room to cpu delta ~ 34.4F (19C) / 25.8F (14.3F)
i'm not too sure how much the gpu is affecting the water temps as my system is usually used for work and web-browsing purposes. i'd say 10C difference is pretty good, a lot better than me