slow down

I've had my computer for just under a year. Windows xp MCE, 3.0 ghz HT processor, 1 gb of ram and an ATI radeon x800xl, When I first got it, I had a little bit of problem with studdering in games, but eventually it went away, after all I was playing games like doom 3, F.E.A.R(when it came out), and half life 2 so I guess I would expect some studdering. Now it seems a year later my computer has aged horribly, I get spyware popups like crazy yet I swept with spysweeper and did a virus scan not to find anything, I play quake 3 and the lag is HORRIBLE, I'm getting 99 fps down to 20 every 3 seconds, the computer if restarted takes about 10 minutes before it gets back up and running takes about 5 to shut down, it's just all around horrible, I wasn't sure where to post this so I did it in here, what could be the cause of this.

P.S. I have installed alot of games now, but I wouldnt' expect a slow down from that

 

IF you wanted to make sure its not malware then follow the
Read And Run me Before Asking For Support
http://forums.majorgeeks.com/showthread.php?t=35407

 

I guess I wanted to check for that, but basically I wanted to know the other possible reasons

 

you windows is messed up. you have to deinstall all unneeded games, clean your registy, and even if that not helps, you will need to reinstall windows.

 

no offense, but are you sure... you're grammar would indicate otherwise.