Interfaces

Two inputs are fine.

checkout the Apogee Duet. Apogee has a reputation for making high quality audio interfaces for mac. It has a couple inputs and is pretty small and portable. It's in your price range - and you could probably use a coupon (most sales ended yesterday) and get some money off the price too. I haven't used it personally. Alternatively you could get a larger firewire interface with 8 inputs and maybe a bit worse sound quality.

I personally like RME interfaces, but they are fairly expensive. I use an RME Multiface II with a laptop card. I got it off ebay for a great deal ($550), but it doesn't have mic pres built in. Lot's of choices out there and decisions to make.....

Also, you have to look at your other gear - what mics/preamps/gear do you have for recording, etc... A nice sound card interface may not be the right choice at first if you are using terrible microphones, and so on...

I use a Line 6 POD Studio UX2. My budget was only about $200, but its a really great interface. Its really easy to use and it has lots of tube and solid state preamp models. It comes bundled with ableton live, reason, and pod studio. I think its for Mac or Windows.