Have you actually done the system restore yet?
If not there's a number of things you can try before resorting to that
Emptying Temp Folder (NOT temp internet files)
Click on My Computer and in the window that opens you will see an address bar at the top, type in C:\Documents and Settings\YOUR USER NAME\Local Settings
In the folder that opens there should be 3 subfolders
HISTORY TEMP TEMPORARY INTERNET FILES
Open up the temp file and delete all the files in there, first time I did this there was over 3000 items in there!
CLEAN UP
Click on My Computer then right click on Cdrive and choose properties, then click on Disk Cleanup
In the first window delete Temp internet files, Recycle Bin and downloaded Program files
SPYWARE SWEEP
If you have adaware and/or Spybot update and run both and then run your AntiVirus program
DEFRAG
Go to start/my computer and right click on Cdrive and choose properties click on tools
Click on errorchecking and when thats done click on defrag now
Reboot the PC
Creating a restore point in system restore
Click on start/all programs/accessories/system tools/system restore
In the window that opens you will have 2 choices, Restore pc to earlier time and create a restore point. Choose create restore point and follow the instructions