To end the debate of which is better, between linux and windows. It all depends on what your trying to do, what you know how to do, and if the OS can do it for you. As a Linux user, and a NT network admin, I would recommend playing with linux. It's fun, different, and it is QUITE SECURE. (OPEN or Free BSD (not sure which) has not had a root Exploit in 2.8 years) So, I'm not going to listen to the Linux is able to be rooted.
The truth is, that you have to decide what you want. An NT box is really easy to setup all of what you want, specially if the software works with NT. But, I know that with my Linux firewall it's great for sharing Internet to people on my network. You connect your machine to my network, and without changing any setting in windows (unless it's not on DHCP) the linux box will give them an IP, setup the internet for them, and put there machine in the DNS table.
BUT, it took a long amount of time playing with linux to learn how to do this. So, what does all this mean. Load RH linux or Mandrake or other Linux's onto that P-100. Play with it, get use to it, and start shifting things over to it, as you see fit. If you think you can't manage a linux server yet, then don't make a linux server.
Just my 2 cents.
LD