Yep, Server 2003 was basically XP-Server. That was a great build, IMO.
The only good news about remaining 2003 installations is they probably aren't used much to visit pr0n sites, so their likelihood of encountering malware isn't as great as the average XP box.
Probably, mind you... just probably... :)
You think too little of people, DG. I used S2K3 Server for a while on a gaming machine. It was the most stable platform I could find at the time.
That said, networks are constantly being scanned for vulnerable vectors. If you’re running a web server from that system, you could very easily be hacked if your firewall NATs to 80/443. My firewall logs are full of attempts against 80/443/3389 from China, Russia, Brazil, etc. They’re always watching for a way in.