I seem to spend less time in Virtual PC and more time in (nested) remote desktop sessions these days. I'm not a huge mouse fan, and when using the keyboard I need to do this when I'm in a windowed remote-desktop session:

• ALT+PgDn / ALT+PgUp - cycle through programs (ala ALT-TAB)
• ALT+Home - display start menu (ala CTRL-ESC)

My fingers still do the regular ALT-TAB / CTRL-ESC the first time round, but after a while I remember to use the alternate shortcuts.

Thanks to Mark Wagner.