Actually, this guide is not bad really. Well written. There are few questionable things like installing some specific software that can be skipped. Also, Firewall is a must. Even if you harden your XP, there are still few ports left open like 135 and 445. They seem to be inactive (wrapper?) when you disable services and uninstall Microsoft Networking, but I would not trust that. Also, antivirus is useless indeed. Better solution is sandboxing or even VM.

I use Win2003 daily on more powerfull PC (i5-2400, 16GB RAM) and its indeed blazing fast. When cache is warm, everything starts pretty much instantly, so SSD is not really needed. Cache FTW!