Suggestions on programs to test stability?

I'd say repeated runs of a graphics benchmark, or a cycling demo mode from a demanding game.

When it was still all the hype, I used to run Unreal's flyby introduction (with all details enabled, max sound quality and maximum definition/AF/AA) for hours to check my systems overclock overall stability.. Right now you could try Oblivion or FEAR cycling demos - but I don't have any idea on how to make them run, or if they have any (I only have FEAR, and I haven't looked).

Another way to test the RAM/chipset/HD capabilities is to start several compression jobs at the same time (say, 2 DVD to DivX encodes and 4-8 MP3 encodes) so as to push these subsystems hard, as well as tax the CPU's thread switching capabilities (pipelines and cache).

In fact, since I usually build a new system or upgrade an existing one when I decide to backup some DVDs I bought, I can say when a system is right where it should be or running a bit too high with tinkering...

Thanks guys! I'm normally not into games, but I realize that a cycling game demo would be a good thing to try. The last game I actually played was "Half Life 2", before that "No one lives forever". It's been a few years. I anyone could point me to a game demo that can be run in a cycling mode, I would be really grateful. THANKS!