Hi Mark - I am not sure about XP-Pro, but I have a machine at work that uses Analysis Office 1.4 SP5 on Excel 2010 just fine on an HP XP (Compaq 8510p).
So I am not so sure you are "stuck". I can also access BI4.1 Launchpad with this machine, no issues.
Analysis Office is also platform independent and does not require BI4.1 either.
I hope this helps