I want to install a UNIX Server and eventually an Oracle database on this server. Client computers will be running Win2000 that have JAVA program(s) written by me that access the database(s) on this server.

Were can I find UNIX? is Sun Solaris considered UNIX? Is there a UNIX Server? or do i just make it a server?

I do not want linux, i want UNIX!! for the reasons to perform the network i have described above.

Linux can do the job you want. RedHat Enterprise (or so I think) come as default with Oracle license.
Linux is an UNIX-like operating system. As far as I know UNIX isn't developed any longer, but there is a whole family of UNIX'es: FreeBSD, OpenBSD, NetBSD, Solaris, HP-UX and many others. You should make your choice depending on what hardware you have and money you are ready to invest.
I heared that Solaris is the best UNIX there is today but it is a bit more difficult to use. FreeBSD is used for large firewalls and servers (hotmail, yahoo, Microsoft), is free and with the CVS and CVSup upgrade facilities as well as with the ports collection of over 10.000 applications it is on the top of my favourites OS'es. About other UNIX'es I cannot tell you anything certain because only these 3 I know.
Alex.

Linux (and other BSD type variants) are free.....Solaris and HP-UX (the other two Unix versions I've used) cost atleast 10 times much more than a copy of Windows. This may sway your thinking that you don't want Linux. My 2 cents....