Eliminating the tiny amount of competition that exists in the health insurance marketplace in favor of one government-run entity hardly sounds like a good idea to me. If you think prices suck now, just imagine what they'd be like with no competition -- it'd be like taxes, basically (far too high).
But you see, matt, there are other countries that have this and that hasn't happened. The United States, which has the most market based health care entity in the industrialized world (with the possible exception of Australia--I'm not sure) spends the most on health care (13.9%% of GDP as opposed to, for example, 9.7% for Canada, 9.5% for France, 8.7% for Sweden, & 7.6% for Britian) . And what do we get in return for this massive spending? Substantially poorer health outcomes.