It's not necessarily true to say that an EF-S lens on an APS-C body (such as the EOS 7D) will be inferior to an EF lens which has an equivalent angle-of-view on a full-frame body (such as the EOS 5D Mk II).
For instance, the EF-S 10-22mm lens is highly regarded, and some even rate it as better than the EF 17-40mm L-series lens. (To be fair, both are about the same price.)
Similarly, the EF-S 17-55mm lens is often said to be as good as an L-series lens in terms of optical performance. (Again, the price reflects this quality.)
If you're a fan of comparing raw optical performance of Canon lenses, take a look at lens review sites such as:
Of course, most of these sites will remind you that lens quality is less important than just getting out there and taking interesting pictures.