I have not used linux for years and years.... but I have recently been looking into it as a platform for internet security, here are a few things I have found you might be interested in
a: Linux is open-source, and you can get it for free as opposed to paying loads for Win2k
b: As it is open-source, improvements are made constantly,
and the OS is stable/reliable - lots of people say even more so than Win2k!
c: It is based on Unix, the OS itself runs on more platforms than Win2k can (i.e Alpha, Intel). It supports SMT which allows multi-processor PC's to make more efficient use of resources, forgive me if I'm wrong, but I think only Win2k DataCenter Server allows SMT.
d: Although Linux can be downloaded for free, I have heard time and time again that RedHat Linux (not free) is ideal, mainly because you get more support, but also because it is supplied with tons and tons of stuff... Because the OS is open-source, there are loads of different versions out there, you would want to purchase a copy (not neccesarily RedHat but..) and get it on CD.
Linux doesn't use NTFS partitions but Linux has a file-system which works along the same lines, keeping user files secure
Linux runs a multi-session environment, which means 10 users could be logged onto the SAME machine.
Ultimately, Linux is more flexible and configurable than other OS's - but it's a leap as it bears little resemblance to any of MS's offerings, If you do make the switch be prepared to learn from scratch.
Experience working in a CLI environment would be most helpful. Most things are done there.
Linux can be secured, and is secure enough to use on the Web, lots of servers run on Linux platforms, so I would suppose you can tighten security just as much as on a MicroSoft platform.
I reckon MicroSoft adds too many bells and whistles to it's OS's in order to make it easier for the end-user, not the administrator. Linux is the other way round. If you are thouroughly PC literate and if Linux likes you, it is more streamlined, powerful, and nowhere near as many overheads to slow your PC down.
Hope some of this helps???