The biggest concern (IMO) with an infant seat is that it has shoulder straps that come out well below the babies shoulders. Some seats are rated to 5 pounds but have high straps that the child has to be 2, 4, or even 6+ months to fit correctly.
Do you have any reason to expect a very small or premature baby?
Current popular carseats include the Chicco KeyFit and the Graco Snugride (not the 22, the 30+ versions). If you have a Babies R Us or Buy Buy Baby around, I would go there and try them out--- pull the straps in and out, practice installing them in our car, etc.. and see how they work with you. The Peg Peregos and Britaxes also seem well liked, but there are a lot of good, safe options.
We went with the SnugRide 32 because it is one of the few seats that fit in the "extra" seat of as 2005 Honda Odyssey.