In your case, AxE, your "router" will be in software on the Windows machine, and your "uplink" is the network card that goes to the DSL, and your "hub port 1" is the other network card (crossover -> Amiga). You must make sure that whatever software you're using on the PC to make it route packets is configured right. It can be a real pain, and sometimes confusing, but it must be sorted out before anything else will work.
Hmm...how is the the "router" software accessed? I too have an XP machine networked with my Amy, but I am using a "hub" with the uplink from my job's network providing internet access, with port 1 being the XP and port 2 Amiga.
I also have samba installed but can't get any consistent results in file sharing. Sometimes it will ping, sometimes not. When it does work, I can see Amiga as one of my "network places" on XP, but if I try to open it it asks for a password that I don't remember setting, so I can't get in.
Can't figure it out...worked fine when I had it networked with a Win98 machine. :-?