I would like to check out Windows7 and install all of my developer programs on it just to test if everything works fine. In the mean time I want to continue my work on my Vista os. Is it possible, using Virtual PC, to install Windows7 and afterwards replacing my Vista installation with this Virtual PC Windows 7?
Take a look at using a bootable VHD. I have one with Windows 7 and use this as my "playground" for testing things like VS2010 Beta 2, Office 2010, etc. The VHD is a single file so it's portable and the performance hit for the virtualization is minimal.
Instead of running a Windows 7 VPC inside Virtual PC inside Vista, you are booting into a Windows 7 VPC - no Vista. works great for multi-booting. Once you're ready to move to Windows 7 as your primary OS, you can still use it in a VHD.
This link may help out... http://4sysops.com/archives/how-to-add-a-windows-7-vhd-to-vistas-boot-manager-menu/