First advice - Linux guests are officially not supported for MS Windows Virtual PC, if you really don't need it don't do it.
Second advice - Virtual PC supports hosting 64bit operating systems (but as Linux is not supported only Windows) - but in some cases I found that I was able to run only 32 bit version (OpenSuse, Fedora).
What I have tried so far
Ubuntu 9.10 - installation ok, but ater "Segmentation fault". After increasing memory amount from 800Mb to 1024Mb the os started, but the performance was REALLY slow. Here is a possible workaround which I didn't tested.
- version i686. I was not able to boot the disk. The screen just blanked at went of.
- version i386. The installation started but after selecting "Install or upgrade" the virtual machine went off.
- version x86_64. this version told me, that I can not use 64bit os on 32bit platform (I'am on 64 bits)
Debian 5.04 - Version i386 net install - after starting the installation the virtual pc went off.
- version x86_64 - this version told me, that I can not use 64bit os on 32bit platform (I'am on 64 bits)
- Version i586 installed fine, but after the "1st configuration" did not finish and system did not boot up correctly.
Mandriva 2010 - version i586 - the installation did not start correctly
Slackware 13 - installation ok, it works now, but so far in the textmode.
UPDATE: ok now it works fine with GNOME.
4 basic steps:
1) Install GNOME version for Slackware.
2) Run xorgsetup to configure the XSERVER
3) Run xwmconfig to configure which X manager do you want to use - select GNOME.
4) Run xinit to start X Server
To Install KDE you just need to add the KDEBASE packages (eg. from GNOME start the package management tool).
If you want to use bigger resolution than 800x600(which is default), than you will have to modify your xorg.conf file, details can be found here:
OK - I was able to get Ubuntu tu run - but realllly slow. Slackware is so far working without a problem.