Innotek Gmbh has released VirtualBox 1.4 for Etch 386 and AMD64. It's a virtualizing solution based on Qemu. Innotek has improved it a lot:

- new kernel module 'vboxsrv' - compiles with on problems on both architectures
- sound works
- shared folders between Linux host and the guest operation system work without the need for Samba installed in the host ( which didn't work with Qemu in Debian anyway )
- USB, Remote Desktop supposedly work ( untested by me as of yet )
- so-called 'guest additions': Innotek provides a CD image full of ( getting automatically installed , at least on Windows guests ) drivers for the guest OS
- clipboard copying , working both ways, supposedly work ( untested )
- nice userspace s/w to control your virtual machines
- ability to take a snapshot of a working VM and return to it later (buggy?)
- no need to grab-ungrab the mouse with 'Ctrl-Alt' like in Qemu ( in Qemu>=0.8.2 that works too, but with 20% CPU utilization )

/etc/apt-sources.list:
deb http://www.virtualbox.org/debian etch non-free

Download a key for secure apt from here and add it with 'apt-key add innotek.asc'

Everything explained in www.virtualbox.org

PS. Be careful taking snapshots. At least on AMD64, taking a snapshot screws up VirtualBox to the point when it segfaults on startup ( when that happened, I managed to rescue my VM installation by saving the hard drive image '*.vdi' of my VM and removing the whole ~/.VirtualBox/ folder, then restarting VirtualBox and adding the VM back from HD image )