AMD 64 Socket 939s may benefit from it a lot. I could be wrong...but socket 939s handle memory the best right now out of any processor. That's good for AMD because Intel has been in the lead in this area for years.
But yea, the socket 754 non FX ones don't do too much. And XP does almost nothing.
"What about using SATA ports and also the IDE ports at the same time?"
Plenty of mobos support both SATA and IDE, but how well they support isn't as clear. I've installed windows xp on an ASUS P4R800-V Deluxe and Gigabyte 8IK1100. Both were nightmares.
I've installed it on an Abit IC7-Max III. Easy as pie. They even had a SATA drivers floppy there for you right when you open the mobo box. Others had a BS "make your own floppy disc with the windows OS you can't install yet because you need these drivers" thing.
Although, that's Abit's flagship mobo, while the others are medium end. So, eh...(I need sleepy sleep).