While this article has some good points, note the date of the article (2002) and how that impacts statements. In particular, there have been several service packs and other updates released since then (XP is on SP2) and the recommendations for memory have gone up. Also note that the document is intended for audio recording/mixing/editing applications, not music serving - music serving is a very low-demand use compared to recording/mixing/editing.
Remember to keep up on updates for Windows (you can use auto-update for this), enable a firewall (XP has a built-in one) and use anti-virus software (despite the article's recommendation). If you do choose to run without AV software, at least make sure your updates and firewall are in place. If you do any web browsing on the system, I also recommend using some anti-spyware software, there are options that don't run all of the time.
There are some odd statements in the article like fast user switching being good for corporate environments (this feature is automatically disabled when joining a domain).
The item that would likely make the most difference is having a dedicated drive (not partition) for audio files, but if the system is only being used to serve music files, it probably won't make a difference.
