|"I don't think Win2000 would be able to handle multi-core processors for one."|
Windows 2000 will recognize dual-core processors as long as Service Pack 4 is installed.
"Prior to SP3 it was not 48 bit LBA compliant, which means it can't configure hard drives larger than 137GB."
This too would be resolved with Service Pack 4.
While the same cannot be said for NT 4.0, in my experience Windows 2000 (specificaly Service Pack 4) has been every bit as capable as Windows XP. My company just upgraded to Windows XP about a year ago, and that was only because Microsoft was going to be dropping security updates for 2000.
Chances are if it runs on Windows XP it will probably run on 2000, even if it doesn't explicitly say so, provided that the programmer didn't specifically and deliberately write out Windows 2000.
iMac G5 1.8GHz "Hero" PowerPC
2 x 1GB DDR PC3200 SDRAM
160GB WDC WD1600JD-40GBB2
Mac OS X Leopard Version 10.5.8