"an air card to use at the office, about a wirelss router for the home, and about networking between the computers."

Yes, those are solutions to getting internet access. No one can tell which you feel is "the answer."

My dad picked up a nice Toshiba Core Duo 17 inch with everything in the 1200 buck region. Today that same model has the Core 2 Duo and is very nice. Just be careful to do your homework on the "air card" since some laptops have PC-Card slots and some have Express Card slots. These are not interchangeable.

One solution could be that EVDO ROUTER (see google.com) if you need to share your connection.