Hyper-V Program Manager
Virtual PC and Virtual Server do not provide a direct user interface to allow people to change settings in the virtual machines. The way that you change settings in the BIOS under a virtual machine is by hitting the 'DEL' key to enter the BIOS during virtual machine boot just like you would on a physical computer.
The BIOS setting information is then actually stored in the virtual machine configuration file (.VMC) under the <cmos> key. If you are interested in changing the BIOS settings for a virtual machine in a programmatic fashion the easiest way to do this it to edit the .VMC file and replace the <cmos> key.
For an example - here is the CMOS string for a Virtual PC virtual machine with a boot order of hard disk, CD-ROM and then floppy:
While this is the CMOS string for a Virtual PC virtual machine with a boot order of floppy, CD-ROM and then hard disk:
Two things to be aware of with doing this is that the CMOS string values are only guaranteed to match when using the same revision of the same product - so you should not do this across product lines (VPC and VS) or across service pack levels (RTM and SP1) - and if you mess this information up your virtual machine may not boot :-)
And I don't have any .VMC file. The only hidden file is Debian.vmsd, which is empty...
Just after it starts running hit Shift + ESC, it shows the post boot screen pressing Delete bring up the BIOS where changes can be made.