Okay....I work for HP, so I guess I should chime in here.
IE7 on XP is almost certainly not the problem. I've installed it on my XP system at work. Where the problem(s) tend to be is in how various web sites have been coded. IE7 follows a more rigorous implementation of the W3C standards. (I forget which) There are a number of things that IE6 allowed web designers to do that the stricter IE7 implementation doesn't allow.
That *might* be the source of the confusion from the HP help desk folks......
-Jeff