Hello Onispop, and welcome to Seven Forums.
You can do a clean install (format) with the Upgrade Windows 7 on your computer if you like to. Clean Install with a Upgrade Windows 7 Version
It depends on what type of Vista Ultimate you have though on whether or not you can install it on another computer. If it's a OEM Vista, then you can only install it on the same computer that you originally activated it on. If it's a retail Vista, then yes, you can install and activate it on another computer as long as it was uninstalled on any prior computer.
Hope this helps,