Unusual reaction on VC upgrade

Hi everyone. This weekend I upgraded from an onboard video display that came with my HP Pavillion, to a GForce 8500GT 512Ram. Although the speed and FPS change is awesome, I find that movments are jerky, unlike before. every few seconds, (when I'm walking for example, it almost pauses for a fraction of a second, then starts again). Not sure what is up with this, since the card is far superior to what I had before. I'll paste my stats here now, and if anyone has any suggestions, I would appreciate it.

CPU: AMD (Unknown model) (2812 MHz) (Dual Core)
Memory: 3070 MB
OS Version: Microsoft Windows Vista Service Pack 1 (Build 6001)
Graphics Card Vendor: NVIDIA Corporation
Graphics Card: GeForce 8500 GT/PCI/SSE2/3DNOW!
OpenGL Version: 2.1.2
LLMozLib Version: [LLMediaImplLLMozLib] - 2.01.16824 (Mozilla GRE version 1.8.1.13_0000000000)
Packets Lost: 627/89837 (0.7%)

also, when I installed the new VC, there was no option to disable the onboard one, and I'm wondering if there may be a bit of conflict happening. And I can't seem to find any thing to disable it.

which video drivers are you using

and for the onboard video your pc's model number might be helpful, altho often there is no way to fully disable it

I'm using the most recent one I could find on the Nvidia site, from May 2008

D May 15, 08
V 7.15.11.7519