Most people here will tell you it's best to clean install, especially if moving from Vista to 7. I would highly recommend clean install in that situation. If you were going from 7RC to 7RTM, I might say give an upgrade install a try but from Vista you're definitely better off with a clean install, although you might get lucky. You can always try it and if you're not satisfied with the results, there's nothing to stop you from then doing a clean install. But if it was my machine, I'd just back everything up, then use Windows Easy Transfer, clean install, reinstall your apps and then use Windows Easy Transfer to restore your data and settings. But make sure you have a separate backup just in case something doesn't go as well as expected. WET doesn't always get everything.