My apologies to everyone involved in this thread.

The problem was not the MacBook. The problem was not the router. The problem was not Tomato or the juiced up wireless.

The problem was that I was polite.

When I left my client's home that afternoon, I politely turned off the lights in the office. Little did I know that the surge protector that the router and modem were on were on a switched outlet (actually, only half of it was switched).

So when she called me back in because she couldn't get wireless, I would go up to her office, turn on the lights, check out the router, find no problem, be able to connect her laptop to the network, then leave the office (turning out the lights) and go downstairs where she promptly would lose internet access because the router wasn't powered.

Upon a second visit, I was in a bit of a rush, and didn't even turn on the lights when I went into their office, so I saw that the router didn't have power.

So yeah, now everything is fine. Thanks for the input and I'm sorry if I offended any Mac owners. It really wasn't my intention to bash Macs.