Hi
It depends on the type of vista that you have.
In principle you can get the similar version of Windows 7 (E.g. Vista
Ultimate has to upgraded with Win 7 Ultimate).
Then you can do In-Place Upgrade that would keep all the Vista data and
applications, and would replace Vista with windows 7.
YMMV according to what specific hardware Software you have. http://www.microsoft.com/windows/windows-vista/get/upgrade-your-pc-options.aspx
Jack (MS, MVP-Networking).