Well, I have a
Buffalo WZR-HP-G300NH, and I'm really happy with it...
The only thing it struggles with (and, I suspect
any wireless router would be the same), is playing full size (3.5 GB+) ISO files of DVDs across the network on XBMC. That's probably a little much to expect of any shared resource at the moment (wired 100 Mbit/s is probably the minimum for that).
Here's a
link to the one I have...