It looks like no one has actually posted a solution to this......the concensus so far is that you're SOL, but I've got a answer.
http://www.microsoft.com/windows/products/...pc/default.mspx
Microsoft released Virtual PC 2007 a few days ago FOR FREE. It is something that no Vista user should be without right now do to the incompatability of some programs. Simply install it on your PC and then start it up with your Win XP (Win 2000, Win 98, Win 95....etc.) boot/startup disk and install the OS on the virtual partition.
This acts as a complete OS, so you will have to install programs through it (vs. running them from vista on it). You wil also have to register XP; you may need to call microsoft and tell the microsoft voice assistant that you wish to "talk to a representative", to get someone in person in order to recieve your activation key.
btw, as soon as you get it setup, go through and install the updates for Virtual PC so you dont have a lagging mouse, etc.
I've been using the chat system fine through VPC with XP SP2 installed on it....along with a few other programs that arent vista-supported yet.