Every time you reinstall your windows you need to go and configure all your wirless settings with password , security certificates and details to start all over again. This is a big problem when you connect to a good number of wireless points.
There are command line tools for that but again you can not expect a normal use to work around with that,. Too Complex. So if you face the same problem its time you try out Wireless Migrator which allows you to back up and restore all your wireless settings, password and security certificates either at some other location or just back to the reinstalled system.
Download Wireless Migrator @Codeplex
Related: How to transfer personal files and settings from XP to Windows Vista