I had similar trouble getting mine connected as well, although I chose wi-fi. Here is one way to do it (I am assuming your cables and so forth are makinga peer-to-peer network. Remember, there are many ways to get it done.
First - Check to make sure both workgroup names are the same on both computers
-run networking wizard on your sentia setting it to ignore disconnected network devices, manually choose how you connect to the internet, and select "this computer belongs to a network that does not have an internet connection." The reason for this is because LAN internet settings should configure themselves so you do not need to focus on internet but rather intranet.
-do the same with networking wizard on your old device (if you do not have it on 2000, install it from your xp disc)
-after being connected restart your other system FIRST allowing time for a full reboot and for the system to become idle again.
-now restart your sentia and allow it the same time. At this point you can go to "view workgroup computers" and both should appear there. If they do not, wait a few minutes longer. Mine took some real time to show up (I believe because it was assigning IP addresses and so forth). According to my father, the reason you want to start up a 2000 system first is because it wants to assign IP addresses in nature being that it is more of a professional or server running system. Hell I don't know, but it worked for me after everything else didn't.
Give it a try!