The short answer, NO.

Why?  There are both technical and licensing reasons.

First, the version of XP included with VPC-Mac is an OEM version, which means that it is licensed only for the "hardware" is was sold with.  In this case, the hardware is Virtual PC.  Almost all PC vendors include OEM versions of XP with their computers because it is cheaper than the retail version. 

Second, the XP included with VPC is crippled to prevent it from being installed on anything other than VPC.  Most PC vendors do this to their OEM XP too, by looking for a particular BIOS or other unique signature of their hardware.  In the case of VPC, XP is crippled by  the removal the files necessary to start and complete an installation.  XP with VPC-Mac is preinstalled and there are missing files that prevent you from doing an installation on any computer, Intel Mac or a regular PC.

The inclusion of the OEM version of XP with the VPC-Mac bundle is the main reason it is cheaper to buy VPC-Mac with XP than the VPC only product and a retail version of XP.  In fact, when you buy VPC-Mac with XP it's nearly the same price as the retail XP alone. VPC-Mac with XP runs in the $200-250 range when purchased new, VPC without an OS runs around $120. 

The retail version of XP runs from $190 up.