For kicks, I installed X2 (and asio4all) on my work Vista-era Dell Optiplex 755, running Xp SP2 32 bit. This machine is terrible when it comes to daily work, and is chock full of enterprise management software... but I digress.
I used the extra content Demo as a test. X2 ran in a very responsive manner considering the state of the system. No issues noticed. Can't wait to get home and test on my "Ubersystem". I'm elbows deep in two projects and I'm going to jump right in with them.