I highly recommend the D-Link 900AP+ ... I'm currently using it in combination with my D-Link DI-614+ and they work great together. The 900AP+ has the ability to act as a wireless access point, as a point-to-point bridge with another access point, as a point-to-multi-point wireless bridge, as a wireless client, or as a wireless repeater... the wireless repeater mode only works with certain D-Link products (DI-614+ is one of them). The price of the 900AP+ is around $100, similar to what you'd spend on the DWL-810 or the DWL-810+ ... And like the DWL-810+ it supports the enhanced 22Mbps 802.11b+ (which is also supposedly compatible at 22Mbps with 802.11g). The only bad thing about the 900AP+ is that you need to configure it a bit more than you would with the DWL-810+ (DWL-810+ is supposed to be more plug-and-playable). However, since the 900AP+ has 5 different functions you could end up utilizing it for another reason should you decide not to continue using Xbox Live.. (WAP, repeater, whatever).
Here's a link to the AP from Amazon.com:
Link - Only $76.64 after MIR!