Democrats currently have a 77-seat advantage in the House: 255 Democrats to 178 Republicans (there are 2 vacancies). Incumbency has its advantages, even in a year like this, so it would be amazing for the two parties to trade positions in just one cycle. But it's entirely plausible that voters will prefer Republicans to Democrats in 2010 by the same margin by which they preferred Democrats to Republicans in 2008. If the 112th Congress is comprised of something like 256 Republicans and 179 Democrats, don't be too surprised.