[jQuery] Thickbox and loading a url with '?' parameters

[sso]

Subject pretty much sums it up.

Thickbox uses ?param1=xx&param2=yy  to load content into an iframe.
The problem is the url I want to load also contains params.   So I end
up with mysite.com/index.php?x=1&y=2?param1=xx&param2=yy  and it only
loads mysite.com/index.php

Any way to work around those or a more viable solution?