Using Virtual Machines
I've found an interesting way to interact with a Virtual Server 2005 R2 Virtual Machine in a fairly performant way: through Terminal Server/Remote Desktop Connection/mstsc. If you are a person with access to an MSDN subscription, install Windows Server 2003 on a machine. Then, go out to the web (
http://www.microsoft.com/windowsserversystem/virtualserver/default.mspx) and install the free Virtual Server 2005 R2 on that Server box. Once the virtual machine is all setup, enable remote desktop connection on the machine and the use Remote Desktop to use the virtual machine. In my experience, the overall user experience and perceived performance is better than when using the Virtual Server ActiveX control from within a Web Browser. And this definitely trumps using Virtual PC.
Using Remote Desktop on Windows Server 2003:
http://technet2.microsoft.com/WindowsServer/en/Library/1e4a44de-2be1-4d29-9387-9f04b79cc17a1033.mspx?mfr=true. The easy way to enable the feature is under the heading "Using System Properties".