Good evening!
The windows XP has an "share internet" in the networks properties. (This, if you have a USB dongle, called Local Network Connection 2 and your ethernet is L. N. C. 1, you can - under properties share this. That is in the pro edition, I don't know about home)
When you do this, you can connect the amiga trough the eternet with a crossed cable, and the PC will act as a DHCP server, and give you a IP adress, the PC will have a static IP adress, and route the TCP/ip traffic to the amiga.
Does this help you?
Give me a word if it works, and any messages you get of error!
Kjartan, Hating Norwegian summers.. :-)