Follow zigzag's advice to save externally a backup image when you have Win7 setup exactly as you want, so that you never have to reinstall again - just reimage using the DVD or Repair CD to "Recover Using an Image" in 15 minutes.
I use Win7 backup imaging which has never failed for me.
http://www.sevenforums.com/tutorials/663-backup-complete-computer-create-image-backup.html
Maybe something about the way you are setting up is messing things up to cause constant reinstalls:
Install programs slowly over time to gauge performance changes. Don't let programs write themselves into msconfig>Startup besides AV and gadgets as they become freeloaders on your CPU/RAM at all times and can spy on you.
Use a lightweight free AV like MS Security Essentials with the Windows Firewall.
Learn to troubleshoot issues rather than reinstalling/reimaging as solution. Google repeat errors in Device Manager>Admin View to see how others have solved them. Study also Performance log on Advanced Tools page accessed by clicking WEI score link at Computer>Properties. Look for cued issues at top of Tools page, Generate a System Health Report.
Clean and order your HD perfectly using state-of-the-art free CCleaner and Auslogics Disk and Registry defraggers monthly.
As Brink says set System Restore points at key times so you can return to when things worked correctly before having to reimage. I have a Sleep issue on one machine here where troubleshooting takes hours, but I can Sys Restore to my "Sleep works" restore point in 5 minutes. You can Configure space for more SysRestore points at Computer>Properties>SysProtection.