Some of the Springdale boards, Abit boards included, have a feature called GAT. The Canterwoods were built with a feature called PAT, one of the things making them better then the Springdale boards. I guess Intel didn't intend to have GAT on the Springdale boards but some mobo manufacturers unlocked it. Intel said recently they were going to prevent that on future boards, but it shouldn't affect any ordered in the near future. I'm not 100% knowledgable on all this, but check at HardForm for more info on it. It seemed like the consensus was that at lower FSB speeds the fact that both boards had this feature caused them to be neck and neck in benchmarks. However, as the FSB rises this feature must be toned down and the more expensive Canterwoods will rightfully move into the lead. There is a long post on HardForum detailing that the Canterwood seems to have a significant advantage once you get to the 240-250FSB range and higher. Whether it's worth the extra $30 between an Abit IS7-E and IC7 is up to you.
I don't know much about the Prescotts, but I do know that if you keep waiting for the next best thing you'll never upgrade. You'll wait for Prescott, then you'll want to wait for the next generation of vid cards, then you'll wait for PCI X, then you'll wait for DDRII, it will never end. Once you feel your system lagging behind your programs it's time to upgrade.