Bob Stern has submitted yet another workaround for using emulated printing in Virtual PC 6.x under Mac OS X 10.3.x "Install the Adobe postscript printer driver for Windows and the Adobe PPD, which Adobe provides for free.
"The Adobe driver allows you to print to a .ps file in Windows. If you save the .ps file in a VPC shared folder, you can print it from the Mac side by dragging it to a printer queue or by opening it in Preview and then printing it. (Preview also can export it to PDF.)"
Also, you may have more success with emulated printing in Virtual PC after upgrading to Mac OS X 10.3.2, as Apple makes the following statement in its release notes: "Improves compatibility for Microsoft Virtual PC 6.1's emulated printing features."