Upgrade Virtual PC 2007 before you virtualize Windows 7 RC

If you plan to install Windows 7 RC using Microsoft Virtual PC 2007, upgrade it to Virtual PC 2007 SP1 (6.0.192.0). Old version (6.0.156.0) will give you BSOD after you install Virtual Machine Additions (Error: Fs_Rec.sys - The driver mistakenly marked a part of its image pagable instead of nonpagable.)
Happily, System Restore works great. :)