Not sure if you've already purchased, but I honestly would not get a Boxee. The client appears to be rather bare bones (I cannot get it to stream in UDP or at 1920x540). I ended up just using a dedicated laptop I had as client.
I'm streaming from LA to Seattle when I visit family there, and can get a good 4Mbit, UDP connection using the PC client. On the Boxee Box, the best I can do is a really crappy TCP connection (due to latency), or use Relay which has higher average bandwidth, but is nevertheless really inconsistent. Also, as I said, no matter what, I could never get a 1920x540 stream with the Boxee Box. So, the thing was a waste of money.
With a PC running the web-based client and connected to the TV via HDMI, I get a very nice, usable 4 Mbit, 1920x540 stream. In theory, I should be able to do better. I have 15+ Mbit connections at both ends and it is running via UDP. But 4 Mbit is the best I've seen this way. Still, it is acceptable image quality.
In sum, the Boxee Box seemed like a great device to use a sling catcher. Unfortunately, it just sucks. I'd save your money.