Problem after hardware upgrade

I Have recently upgraded my computer hardware, I have replaced the motherboard, CPU, Graphics Card, RAM and power supply.

I have done a clean install of Win XP Home and have downloaded and installed all updates.

I have gotten a few new games but they are not working properly it seems that when a lot of detail appears on the monitor it starts to stop and jump rather than run smoothly.

I have gotten all drivers for my hardware updated but still doesn't work smoothly. Have also played around with some settings in windows but still no good.

Computer is:

Motherboard: Gigabyte GA-MA770-DS3
CPU: AMD Phenom 9500 Quad Core
Graphics Card: Palit Nvidia GeForce 9600GT
RAM: 4Gig Crossair DDR2
Power: Antec 550W

This is all above the requirements for the games that I am trying to play.

Also I have 2 hard drives using the IDE connection on the Motherboard and my 2 DVD Rom Drives using an IDE Controller Card plugged into a PCI slot could this be affecting the performance.

Also since installing all programs and drivers again I have a wireless keyboard and mouse that I can't get working windows pick up that they are there but I cannot use them.

Any Help and Advice would be appreciated.

Thanks,
602AJ