Network Upgrade

To upgrade your servers, you should plan hardware requirements first (CPU, Memory, HDD, etc.). You should also take in count that you will have another OS (you may create baseline of you existing configuration to look how your present system handlesall tasks), and make estimate for 2-3 years growth for future.

For sofware migration you should look Microsoft's White Papers on NT4->W2K migration. If it's just "standalone" server, it's easy and painless. In case you upgrade users environment, you have much more involvements, since you should migrate from "Domain" to "Active Directory" (see papers).

Good luck.

I am sorry, i didn't give it at the first time. But you should learn how to find answers at MS site. These links I have found in 2-3 minutes:

Planning Migration from Windows NT to Windows 2000
http://www.microsoft.com/technet/treeview/default.asp?url=/TechNet/prodtechnol/windows2000serv/plan/migntw2k.asp

Planning a Web Server Migration Project
http://www.microsoft.com/technet/treeview/default.asp?url=/TechNet/prodtechnol/iis/deploy/planning.asp

Managing the Migration Process
http://www.microsoft.com/technet/treeview/default.asp?url=/TechNet/prodtechnol/iis/reskit/iis50rg/iischp2.asp

Upgrading a Windows NT Domain to Windows 2000 Active Directory
http://www.microsoft.com/technet/treeview/default.asp?url=/TechNet/prodtechnol/windows2000serv/deploy/upgrnt.asp

Windows 2000 Migration Checklist
http://www.ust.hk/itsc/desktop/pc/windows2000/preparation.html

Windows 2000 Migration: Best Practices
http://www.netiq.com/Downloads/Library/White_Papers/Migrating_Windows_2000.pdf

... and much more. But since you didn't provide more details on your project, I will limit a list with these. And as 2 cents tip, go to www.google.com and type "windows 2000 migration checklist".

Good luck.