Upgrade from Server 2000 to Server 2003

You are correct. It is just a simple ADSL modem that connects to the Linksys router and NATs everything.

Would the VPN work with this type of NAT?

You should be ok with IPSec using ESP but just be aware incase you start to get into any problems.

If you are using Windows 2003, you may want to us PPTP anyway which i beleive does work through NAT. PPTP isn't as strong as IPSec however you can now use L2TP which is much more secure then PPTP.

Windows VPNClient doen't natively support IPSec so you may be forced down the L2TP route (or the less secure PPTP)

Cheers

Thanks for all the information!

You suggested that I complete a full reinstallation of the server, but wouldn't that be a great deal of work. I would have to backup all data and reinstall all the programs, backup software, etc. How can I justify the cost to my client?

Cleaner installation therefore more reliable build. Depends on how critical the service is, also its worth bearing in mind that the software may need re-installing anyway if the versions you have installed are not compatible with Windows 2003.

Good point, I need to check if all the other software is compatible with 2K3. I will look into it.

you may end up spending more time then you thought getting the software thats already installed to work.