Firstly I would uninstall SpyBot as Windows 7 does not require such Registry Cleaners.
Then Run SFC to check the integrity of all Windows 7 system files:
Click on the Start > Type in search cmd
Right click cmd at top and Run as Administrator
Type SFC /scannow
at the prompt
(Note: there is a space between SFC and /scannow) http://www.sevenforums.com/tutorials/1538-sfc-scannow-command-system-file-checker.html
You could also try:
Free up the startup.
Click on the Start button
Type “msconfig (without quotes), click the resulting link. It will open the System Configuration window.
Select the “Startup” tab.
Deselect all items other than the antivirus.
Apply > OK
Accept then restart.
Your Anti-Virus maybe hogging your resourses (Just a suggestion)
I would recommend MSE:
Microsoft Security Essentials.
Has better compatibility & stability compared to other antiviruses/internet security software.
Has a light footprint and is free. Microsoft Security Essentials - Microsoft Windows
Uninstall all unnecessary programs that you no longer use.
Also Press Ctrl>Alt>Delete simultaneously and click Start Task Manager then choose the process tab.
Look under the memory column and it may give you a clue to what process is using the most RAM.
Hope that helps