I started installing VS 2005 in the VPC and then I got to the point where I wanted to join my work domain.  The network person came by and because it's a domain controller she told me it could not be joined without a painful demotion from domain controller process.  I did some research also and realized the VPC will die in October of 2008 no matter what type of keys you input into the VPC.  So yet again I started from scratch installing my companies software, rather than using the MS VPC.  I had a little bit of a falling out with my old VPC, since LRS owns most of the codes and when I switched to a laptop the copying process did not go over too well.  I have also realized that I need to work with more Differencing Disks, because if I make my VHD read only and work with a Differencing Disk all I need to do is re-create a new one if I break the VPC.  For some reason I am constantly breaking my Sharepoint VPC's for the strangest reasons.  There is that one problem I had where it just decided to no longer boot Sharepoint and did not shoot off any error messages.  Then there is the time I converted to Active Directory and broke the entire VPC without realizing what I was doing.  I am going to strongly urge you guys to work with a Differencing Disk and create your own VPCs if you have the software.  If you don't have the software, then I would use MS's VPC.  Unfortunately, if you don't have a Server 2003 Key from RTM 2, then you are going to have to continuously delete the VPC and reinstall it from the rar files.  Good luck.