via the sysinternals website Microsoft have released a new free P2V tool – Disk2VHD which creates a vhd of a machine, using VSS to snapshot the machine while it is running.

While this does not update the HAL and inject drivers you could use it to convert a running Win7 machine to vhd and use it to boot that machine from vhd with little or no fuss or just to create a bootable backup.

you can get it here:

http://technet.microsoft.com/en-nz/sysinternals/ee656415(en-us).aspx