i play warcraft all the way from australia.
wifi or wired, latency concerns aren't all that problematic from my perspective

as for the wrt54g, if it can support dd-wrt, and you'll have to check the serial number label for the hardware id's, there's like 6+ kinds of wrt54g,
if you put ddwrt on there, it will have a much better port forwarding "wizard" setup than the linksys defaults.
the patch server needs to use bittorrent to talk to your PC, so it needs the tcp 6881-6889 range, as well as tcp 3724 for opening up a dialogue with your machine and tcp 6112 for, something else.
i.e.
http://www.portforward.com/english/rout ... loader.htmand
http://www.portforward.com/english/rout ... loader.htmif your ISP has a games page, they might have local copies of the required patches, i.e. to get from 2.0 to 3.0.9 is going to use 1gb+ of downloads to get from 2.0, to 2.3, to 2.4, to 3.0, to 3.01, etc., to 3.09. using your ISP's game download mirrors will help with the speed, but also with the speed of patching, manually patching is much much quicker. all you have to do is install each patch, or overwrite the partial patch file with the fully downloaded ones, and start up wow (repeatedly) until it's ready to go.
http://www.wowwiki.com/Patch_mirrors