Try "ESET Smart Security 4" instead of AVG etc... works great under Win7
Some hacks to improve Win7 performance....
- Disable "Superfetch" and "Windows Search" via - > "Start" - type in - "msconfig" ->Tab -> Services -> Look for "Superfetch"/"Windows Search" and disable it....
- Click on "Startup" and check if you need all these items on system-startup (java-runtime, adobe reader sl, etc...)
Check your "Power Options" -> may your setting is set to "minimal" instead of "always on/max power"