Balance... that is the thing to go for. If you have one subsystem out of balance it will affect the overall experience. Luckily W7 has the Windows Experience Index built in.... and there is a way to get accurate readings.
Navigate to C drive/ Windows/ Performance/ WinSAT/ DataStore/ delete everything in there/ back out and reboot, and then go to Computer - Properties and note that the Windows Experience Index will indicate that it has never been run. Run it and you will get an accurate reading now, and can tell if you have a weak link.....