Microsoft Virtual PC 2007 RTM
Looks like Virtual PC has gone to RTM today also. Both the 32 and 64 bit versions are available.
http://www.microsoft.com/downloads/details.aspx?FamilyId=04D26402-3199-48A3-AFA2-2DC0B40A73B6&displaylang=en
Update: I have uninstalled the RC and have installed the RTM. I have updated the VM Additions in my two virtual machines and everything seems to be running so far. Next step, keep your fingers crossed.