Unless they changed it, MSE doesn't run on Windows XP last I checked.
Maybe I'm crazy. I guess it does run on Windows XP.
It appeared to run fine on XP (and silently ate all my keygen's in the process)
<sigh> it ran fine on XP/SP3 until I removed it in favor of another AV.
The $9.99 deal at NewEgg is back up...at least for now.