i just upgraded from a q6600 to a core i5 750 neither oced , what i notices is the cpu usage for example the programs and games i ran on the q6600 is exactly the same cpu usage on core i5 i would had thought the cpu usage would have dropped since it a newer processor.
You won't see a significant difference from Q6600 to i5 750 when playing games. The design is different between the two. The i5 is a more efficient CPU and is a true quad core unlike the Core 2 Quad, which were more like Core2Duo X2.
The usage would be the same, but the time it uses should be shorter. Try running some benchmarks like Cinebench or SuperPi if you wanna see the difference.
ok i just thought there was somethign wrong with the cpu jsut caus elast time i upgraded form a p4 ht 3.2 to a q6600 i saw a 25% drop in cpu usage and iw as expecting the same with i went to the i5 , it does feel faster than the q6600 and run cooler buts that probaly my antec 900c case