To Upgrade to Project 2003 or Not

Hello,
I am trying to determine the feasbility of upgrading from Project 2000 to Project 2003. We are running Windows server 2000 and are not planning on upgrading to Windows Server 2003. Would the availablity functionallity of Project 2003 be usable/cost effective in light of the constraints of using Windows 2000 server?

Any insight/comments would be helpful.

Thanks In Advance