Hardware Acceleration

Video playback freezes while in full screen but not in minimized. I have discovered that turning hardware acceleration off prevents the video from freezing up but i am wondering if this PC is still running at full capacity with the acceleration turned off?
It dose not matter if am watching Hulu, Netflix, utube or a dvd that is running in the drive. Video games seam to run fine be it a game that i installed from the disk drive or got of steam, games for windows live.

I guess what i am asking is, Can turning off H.W Acceleration in video hamper the other uses that this machine dose(F@H, Video Gaming, Photo editing,listening to internet radio stations)?

Phenom II 940 3.3Mhz O.C
Biostar 790gxe 128
4 ghz PQI ddr2 900
Evga 285 stock no O.C
WDC WD2500KS/WDC3200AAJS
ATAPI iHAS120 6 ATA Device