Can I use a wireless-g broadband router as a wireless adapter to connect a computer

[Anukama]

to my home network? I have a Buffalo Wireless-G 125 High Speed Router & Access point that I have been using with a Buffalo notebook adapter for awhile and am very impressed with the High Speed Mode, and wanted to connect my desktop with this as well. Sadly I've found that Buffalo is currently being sued and has halted shipment of all wireless products in the US. I haven't been able to find any Buffalo High Speed PCI cards or USB adapters, but I have found many of the High Speed routers the same or similar as the one I'm currently using and was hoping to find out if I could connect one of these to my desktop to be used to access my network, instead of establishing a network. I found a Buffalo Wireless-N Nfiniti PCI card for only $35.00 but I haven't even opened it yet because, as far as I can tell, it isn't backwards compatible with the High Speed Mode of the Broadcom 54G chipset. I know the Buffalo wireless-g MIMO Performance products have this ability but I haven't found an adapter for that either.
I am wanting to use a router to connect my desktop to my "wireless" network, "router" to "router" in case this isn't obvious from my explanation. i.e: desktop>LAN>router connected wirelessly to router>DSL modem>DSL line. Thank you!