I think it is unlikely that the problem lies with the router. A computer, regardless of operating system, connects to a router using TCP/IP protocol and either an ethernet cable or "wirelessly", again using industry standard protocols - 802.11b or 802.11g.
I have a MacMini into which I plug a Belkin USB Wireless Network Adapter and this connects fine to a Linksys WRT54GS router with Virgin Cable.
The other routers I use are a D-Link DI-524 and Netgear WGR614, but it really doesn't make any difference.
Can the Mac connect to the router with an ethernet cable?