Mouse lagging in games that my computer should be able to run efficiently

I have a decent computer that I bought in January from Ibuypower. It's a Athlon 64 3000+, Nvidia GeForce FX 5200 128mb, 512DDR, and so on. I will give more details it if is necessary.
Ever since I bought this new computer it won't run games with higher resolutions than the default resolutions. For example, in both Max Payne and UT2003 (single player), if I up the resolution even one selection the game becomes slower almost to the point of being unplayable. In addition the mouse becomes very laggy and unresponsive. There is about a second delay from when I move the mouse until the cursor moves. Now I have updated my mouse (Logitech MX500), video card, and processor drivers and nothing seems to help. Shouldn't my computer at least be able to run Max Payne on it's full settings? And why is my mouse so laggy? It frustrates me because for the longest time I had a computer where I always played games on the lowest settings. Now I have a decent gaming computer but I still can't enjoy the graphical settings of years old games! Can anybody please help me? If you need any more details or anything, just ask, I will do whatever I can to help figure out my problem.

 

Check what rendering mode your running your games in.

 

Rendering mode? Sorry, I'm not quite sure what that is or how to check it. Is that like Direct3D or OpenGL?

 

Yeah. perhaps an in game setting