Maybe I need to get some sleep, or some coffee, I'm having rouble following what you have said. Here are just a few observation that I can throw out now:

I'm not at all sure what you did with FIPS, but it does sound like you make space for an install. I'll assume that that is correct and not further concern myself with that.

You talk about installing Debain Sarge. I've repeatedly suggested Etch. Etch is often also called "testing", but it is pretty stable and I see no reason to use Sarge, which has a somewhat more difficult install process (they learned a lot by the time etch was made and it shows). Since Knoppix contains a lot of Etch code I believe that Etch should be considered at least as stable as Knoppix. While you are certainly free to install Sarge, and your hardware is old enough that you are not likely to come across things that were not supported in Sarge but are in Etch, my recent insall experience is with Etch, it's been well over a year since I last installed Sarge and I don't trust my memory on it.

When installing Debina Etch there comes a question for the type of install that you are doing, including options for things like file server or mail server or (if I remember correctly) print server and one of these choices is Desktop Install. That is the option that you take to get Gnome during the install. There are also choices like this in Sarge; I'm sure because when I installed Sarge I got the GUI at install time, but the wording might be different or it might have been presented in a different way, I somewhat recall a check list of things I wanted but it's been too long ago for me to be sure enough to give ohers advice. You very likely can apt-get gnome or kde now (if you apt-get kde you bring in a lot of extra kde applications with it, I think you need to apt-get something else like kde-default to get just the core GUI) . But I have not installed gnome this way and don't know if any extra setup will be needed later; I've always done it by selecting desktop install during the install process.

As to your NICs, I'm completely confused. It sounds like you might have an on-board NIC that you are enabling or disabling in the BIOS. But you system is so old that this understand does not really seem likely. And you seem to call one of the "network adapters" a "scientific-atlanta WebSTAR 2000 series cable modem". A cable modem is not a network adapter. It is the thing that you plug attach the network adapter (NIC) to to get to the outside world. I can tell you two things here:

  • 1) I always use a router when connecting to the Internet. I consider them critically important in providing hardware firewall protection. And they will make most other network connection problems "go away". These have become extremely cheap, you can get an 802.g wireless/wired router for $9.99 after rebate this week at CompUSA and you can get a Linksys 802.b router for $1.99 after rebate today and Monday.

    2) Debian (both Etch and Sarge) has always identified my NICs properly at install time and uses DHCP with the router to get all of the needed setup information. I know a net-install with DSL (I have DSL) would be difficult if not imposiable without a router, but I expect that it would work OK with a cable modem, but some cable companies play games with MAC addresses and such, and a router would resolve this issue for you.