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#11
Certainly the best thing to do is a clean install. Win 7 does a good job of putting your old files in a folder Windows.Old. You should still backup to be on the safe side. When installing your programs again, you will have all of your data files in the Windows.Old file to make things less of a burden. Just reinstall the programs and move your data files to the proper folder for the program. You will be glad you did the clean install.
Since you need to backup anyway, get the cleanest possible install by booting from the DVD, selecting Custom install and then Drive Options to delete all partitions, create New as you wish, then Format before installing to the first partition. The installer will see Vista at bootup and allow Upgrade key.
The Win 7 installer is nearly driver complete with updates added during install if you stay connected to the internet, more coming in via Windows updates. Others can be found along with favorite apps at the Support Downloads page for your computer model.
You can also back up your drivers by saving the Vista windows/system32/drivers file to browse later for any drivers missing in Device manager.