New version of Virtual Server (PC) extensions released
If you are running virtual machines with Windows 2003 Server SP1, you will want to grab the latest Virtual Server Additions, version 13.552, which were released on Jan 20, 2006. Once you have run the file and upgraded your Virtual Server 2005 install, you can use the directions here to update your Virtual PC images to the latest additions as well.
EDIT: I neglected to post the link to the download. The updated Virtual Additions can be found here.