Very sorry to hear it, JLR 

Since you have to replace the motherboard, why not go whole hog and get something nicer than a Duron 1000? 
I too am using an Athlon XP 1700+ in my cab. Haven't actually hooked it up to the cab yet, but I've played MAME on a monitor and it's smooth as silk.
It's amazing how cheap computers have gotten these days. Total bill for my computer was:
$115   Athlon XP 1700+
$70     Shuttle mobo w/VIA KT266A+ 
$30     Case + AMD-approved 300W power supply
$0       "Blowhole" case fan (came w/case)
$0       Sound (integrated w/mobo)
$32     Radeon VE-based card (eBay)
$0       D-Link NIC (had lying around)
$0       256 MB DDR (swiped from other pooter)
$20     30GB Quantum hard drive (classified ads)
$18     50x Afreey CD-ROM (eBay)
$18     ThermalTake Volcano 7 chip cooler
...for a total of $303 for a computer that's darned near the top of the line for today, and would blast to smithereens the top of the line computer a year ago. If I'd had to buy the RAM and NIC, it would've been maybe $80 more. Just amazing.