Have you updated to the latest and greatest video drivers from Nvidia? Also, download and install the newest version of Direct X, which is Direct X 9.0c (which was recently updated). Even if you already have Direct X 9.0c installed, download and install it again due to it's updates.
If this doesn't help, then it may be programs that you have running in the background. Try going HERE
and disabling some programs at startup (that starts when windows starts) as certain programs will rob your computer of resources (like cpu speed/power etc.). Be sure to read the instructions...it's not terribly difficult, but can be tedious. If in doubt about a program, then just leave it be!
Let us know if this helps!
War produces veterans, wounded both physically and mentally. They have sacrificed for us.....and it is now our job to help these veterans, as they have already helped us in ways we will never know, in ways that we cannot fathom, and in ways that we take granted every day.