Getting bad framerates in Team Fortress 2 and Counter Strike: Source

[AgentMatt]

On Wednesday night after I was done playing Team Fortress 2, Steam updated and wanted to restart so I just turned off my computer. The next day, I turn on my computer and start up Team Fortress, all of a sudden I'm lagging, so I lower the graphic settings, still lagging. So I quit trying to fix it and play Counter Strike, and what do you know, I'm getting bad FPS in that too.
Has anyone else had this problem or have a solution for it?

System specs:

CPU: Mobile DualCore Intel Core 2 Duo T5450
GPU: NVIDIA 8600M
RAM: 3GB
OS: Windows XP 32-bit SP3

Edit: The lagging mainly happens when there is a lot of things happening, like a group of people shooting each other.

[DrumStick]

Steam update, maybe update your driver, i don't know what else i'm not that tech-savvy.

[AgentMatt]

My graphics card drivers are up to date, I also system restored back to Tuesday, but Steam updated again and I was still getting bad FPS.

[CombineGuru]

Make sure you don't have windows "Power Saver" plan enabled. I turned it on on my Acer once to try and keep the idle CPU temp below 50, and was getting 1fps in all the games for weeks until I worked out what it was.

[editline]04:53AM[/editline]

oh wait nvm, you've got XP.