My 5 year-old computer, that's been holding up very well considering its age, may be beginning to show it. This has never happened since my upgrade in May, but now I'm getting a problem with my framerate while playing games. It'll mostly stay at a good 30-35 FPS most of the time, but every 3-5 seconds, the game will almost freeze for less than a second, and then repeat. This is disrupting my experience, and is very annoying. I haven't tested all of my games, but this has happened in Team Fortress 2 and Left 4 Dead 2.
AMD Athlon X2 @ 2.1 GHz
NVIDIA GeForce GT 240, 1024 MB video RAM; GPU @ 550 MHz
3.00 GB RAM
Windows Vista Home Premium SP2, 32-bit
Any help would be appreciated.