What you need is a wireless bridge, probably a "G" wireless bridge (otherwise your whole wireless network will run at "B" speeds). There are a couple of brands out there, including Linksys, SMC, and D-Link. Go to the companies' web sites and see what they offer. I'd advise against buying Microsoft's wireless XBox adapter, since it appears to be "B" only.
Most network equipment for small and home offices features setup through your browser, so there are no OS-dependent issues. Good luck.