Next update the BIOS from Windows which is the safest method. Follow the Read Me steps exactly.
Test your memory using memtest86 CD
for 5-6 passes and maker's HD diag/Repair full CD scan: http://www.tacktech.com/display.cfm?ttid=287
Next back up your files, gather your program installers, wipe the HD of all code and clean reinstall to overcome the likely effects of an in-place Upgrade gone bad: Clean Install Windows 7 Clean Install with a Upgrade Windows 7 Version
Wipe the HD using this method: SSD / HDD : Optimize for Windows Reinstallation
The installer is mostly driver
-complete with newer arriving quickly via optional Windows Updates. Any drivers
then missing in Device Managercam be found on the Support Downloads webpage for your computer or device model. Only change out drivers if performance dictates, first the chipset then display driver.
Install programs slowly to gauge performance after each. Don't let any programs write themselves into msconfig>Startup besides AV and gadgets. Use free MS Security Essentials for the leanest least intrusive AV.
When you've finished, clean and order the HD perfectly with CCLeaner ("Run CLeaner" and Registry tabs) then Auslogics Disk and REgistry Defraggers monthly.
Watch the Event Viewer>Admin View closely to google repeat errors to resolution. In Advanced Tools also watch Performance Log and Generate a System Health Report.