I can't see a way of doing this in GA. What I can do is find out how many Windows users were on IE7 over a given time period, but not how many Windows XP users were on IE7.
Does anyone know how to configure GA to provide me that info? Basically what I'm looking for is the total number of users running XP who were also using either IE7/8/9. I don't mind running the three browser version queries separately and adding them for a cumulative figure but I can't even get it to refine down that far.