UltraB. I am envious. Always wanted one but the package was too rich for my blood at the time. Opted for the Soltek FRN2 instead. No regrets. Very stable boards. Still have a virgin one that I haven't even removed the stickers from. Final revision too. After they switched to the Japenese non-plague ridden caps.
I have an Ultra B as well with an Infinity plus a few Abits for good measure.
I'll go ahead and say a Socket A really doesn't need much more than 2.0v's to max out the chip, perhaps 2.1v's and that's it.
Any more and you're just cooking the chip.
@Susquehannock Check around for a good Abit NF7/NF7-S 2.0, Abit AN7 or even a Asus A7N8X Deluxe 2.0 or A7N8X-E, those are good clockers too and cheap enough. STAY AWAY from the LA versions of the A7N, total crap boards with a BIOS having 0 options for tweaking and also beware the Abit NF7-M, it's a crap board too.
You'll probrably have a harder time finding a good chip than a good board for Socket A nowadays, esp a good mobile but I can suggest an XP 2400 T-Bred since those tend to be good overall regardless.
An XP-3200 Barton is nice but be weary of overpaying, I guess it's up to you what getting one would be worth but personally I woudn't give over $20 for one. If you look around eventually one for a good price will pop up.
Most of what's on fleabay nowadays is just the leftovers meaning mostly crap chips.