What'll it be?  Win 89, ME, or 2000?  (Or Linux, Free BSD, BeOS...)  This will be a quick and dirty rant on the pro's and con's of each OS.  I'm not going into much technical detail.  I just want to give a quick overview of some pro's and con's of each OS.  If you're not sure what you want, check it out.  If you want to know more about what makes windows 2000 different from windows 98/ME, read on.

Windows 2000:
This is a work-horse OS (operating system).  Power, efficiency, and a fist full of options...
The good - It's stable.  It's efficient.  It's Plug-n-Play compliant.  It's easy to setup.  It has a fairly simple interface.  It's got a lot of power.  It may run 32 bit programs faster.  It's multi-processor enabled.  Good Multi-user support.
The bad - It has more overhead.  It will not run multimedia stuff as fast.  Games will not run quite as fast.  It's harder to tweak.  It's bigger.  It's more expensive.

Windows 98/ME:
These two are very close relatives so I'll stick them together.  This is the Toy OS genre.  Quick, less stable, and more passive.  The OS will step aside and let the programs have their way with the hardware on your system.
The good - It's tweakable.  It runs games faster, usually.  It usually does better with multi-media.  It's not as powerful, but you aren't locked into it like you are with 2000.  (Not an issue for most users.)  It's very well supported by software and hardware.
The bad - It's unstable.  It leaks memory.  It doesn't control programs/users as much.  It will step aside and let programs have their way with things.  (Good and bad.)  It lacks a lot of multi-user functionality.  Only supports 1 processor.  Does not work as well with RAID, SCSI, or other higher end hardware.

Linux:
Compared to Windows, Linux is very secure.  It's much harder to break into.  It has better multi-tasking, networking, and multi-processor support.  It is a very robust OS (but it's graphical user interfaces are still a little primitive.)  Linux is not as user friendly as windows.  It is not as well supported.  There are only a few games that will run on it (Quake III, Unreal Tournament.)  A lot of hardware isn't supported.  (And a lot is.)  IT'S FREE.  (Or almost free, if you get a specific distribution.)  It's open source.  This OS is designed to be more workable.  If you need power and the ability to totally configure your OS, this is a good choice.  For a new user, you may want to proceed with caution before jumping in.

BSD:
BSD = Unix for x86.  There's several flavors.  This is even more secure and powerful than Linux.  A lot of Web Page Hosting companies run BSD on their servers.  It's almost un-hackable.  (If you set it up right.)  It's a bit less well supported than Linux.  (But Linux stuff is usually ported to BSD pretty quickly.)  If you want power, I mean true power, go with BSD.  If you need a secure, fast server, BSD will do it for you.  It'll run faster than Win2K on a slower machine.  It's very efficient.  But, like Linux, it's not for the faint of heart.

BeOS:
BeOS seems to be loosing popularity.  Development on it seems to have subsided.  It's a good multi-media OS with a lot of potential, but much of that potential remains untapped.  It's pretty easy to install and play with if you want to check it out.  (Uninstalls easy to.)  It has a nice GUI (Graphical User Interface) front end.  There are some programs (not a whole lot, but enough to keep you busy for a while.)