In your case (rented house) I would recommend a Wireless solution ... Plug an access point in upstairs, then to get good signal downstairs (if necessary) get another access point that will bridge off of the connected one, extending your range.

I would look for access points that are future compatible if possible ... like those that will allow you to change a pcmcia card out for a newer technology. Orinoco (Lucent) does this, and I believe Linksys is on the right track with their newer access points.

802.11b is pretty available now and moderately inexpensive. Very cool. This is what I run at home, and what they have around my school. It's a bit faster than your cable modem or dsl line, so it won't be a bandwidth constraint. 11 Mbits/sec ... so a little faster than 10BT right?

802.11a is the new cousin to that. Some manufacturers are getting near 90 Mbit/sec in "turbo" mode ... that's almost filling a 100BaseT pipe. These products are out, but not every manufactuer has advertised support. Proxim has and they've got a few products out ... a little pricey but very fast.

Orinoco has a good backbone to support these new technologies, and a very strong reputation for support, compatibility, innovation, ... this is what I would probably get in your case.