The remedy for the problems you describe is a clean install. It would have probably fixed the Vista, too.
The corruption you describe in Vista will be transferred in-place into Windows 7 by upgrading. If there was ever a time to clean install, it is under your circumstances and looking forward to the best OS ever.
Back up your files, gather your program disks, installers, boot from the DVD, plug ethernet and "Connect to the internet during install" to get latest drivers
, Updates," select Custom install, use Advanced drive tools to set up partition(s) as you wish, format and install.
Afterwards, get remaining drivers/Updates from Windows Updates, check the Device manager for any missing drivers which you can find, along with any favorite apps, on your computer manufacturer's Support Downloads page for your model. Adobe reader/flash and Java runtime/free Ofc suite are on their sites.