First can I suggest you use Utorrent instead of Azureus? Utorrent uses about 1/10 the memory and only needs a single 170k file to run!
Either way you should enable universal plug and play (UPNP) on the router and instruct the torrent application to use it. This way the ports will be forwarded automatically and you wont need any static IPs or permanently open ports. Try to get firmware version 1.01.18 for V1 or 1.00.6 for v2 as it has a UPNP fix.