XP optimization for audio

I've been looking over a PC optimation guide for Windows XP from a site called www.area709.com. I've made some of these changes, although I have to be careful since our computer is mostly, but not specifically for audio (may be able to get a second one for my wife later).
1) I have no significant issues right now, but have'nt noticed any differences in performance. What would I look for to observe better performance in audio applications?
2) Has anyone else seen this guide?
3) If so (and you're someone who knows about such things), can this guide be rated step by step as to its relevance to Sonar and which adjustments are most useful/important, and which ones are not so crittical?
I know very little about PC's and operating systems, I just use 'em the best I can and try to understand a bit here and there.

Also check your system's DPC latency with this tool.

If you're working at low-latency, having low/consistent DPC latency (no large spikes) is absolutely critical.
This will have a more dramatic impact than most single tweaks.

High DPC latency and DPC spikes are virtually guaranteed to cause dropouts/glitches/etc.