help with bittorrent please - won't start

I've been attempting to set up bittorrent on my computer on my home
network. I have previously had that working when I had DSL, but last
summer I changed to cable modem. Currently there is a Motorola SB5120
cable modem, running to a linksys wrt54g wireless router, then a linksys
ezxs55w switch to which I'm connected. I've tried with both Gentoo and
Ubuntu with qtorrent and azureus - the result is always a failure to
connect. If I try the azureus nat/firewall test I always get a nat error.
The motorola surfboard has basically no setup parameters. I've set port
forwarding on the wireless router.

Anyone have experience with a mess like this?

thanks in advance.