So just to clarify, Doom 3 BFG will absolutely not work on Windows XP?

I've read if you update your Visual C++ files, it will. True?

You know, I have this game disk and I have not even tried to install it yet on my XP machine.

However it is an Open GL game, so it should run on XP. I guess your results will vary. Some have reported it launching on an XP machine.