Ok first off, with the 2WIRE router/gateway combos, they have internal antennas, so you can't attach a bigger antenna . So if you havent already, you need to turn up the transmitting power on the device. I went to a relatives house with my laptop, and I was getting poor wireless signal everywhere I went in the home (2 to 3 bars) (they were also using a 2WIRE too). As it turned out, the 2WIRE's transmitter's power had been turned down past half power (set at 4 instead of 10). So before you do anything else, you need to make sure it is turned up to 10, which is full power. After I did that, I was getting 4 bars+ everywhere. To do that, you'll have to access your router's/gateway's setup page.

If that doesn't give you effective coverage, you might try wireless repeaters/extenders. I'd buy one with a removable antenna so I can put a bigger one on it if the signal is still not getting where it needs to be. Here are some examples:

Amazon.com: Linksys Wireless-G Range Expander WRE54G: Electronics

Amazon.com: D-Link DWL-G710 Wireless Range Extender, 802.11g, 54Mbps: Electronics

Amazon.com: Belkin F5D7132 Wireless-G Universal Range Extender: Electronics

Borgslayer