Today Nvidia has introduced a software that does what the creator of WCPUID H-Oda! did with "SoftFSB" years back: Allow "on the fly" clock control from within Windows. It also supports on-die thermal readings from the Athlon CPU's that supports it and also shows a host of voltages including chipset voltage.
I had a quick run with it on my unstable Abit NF7-S and came to the conclusion that the on-die temp reading does not work, neither the system temp... If it works better with other mainboards we will see when I decide which one to buy. The reported CPU voltage was also way off however I could still change the clock without rebooting... The program is well worth a try and will hopefully reliably show all those temps and voltages in future revisions.
UPDATE: The clock control seems broken also, after a few more retries the computer hangs... Thanks Didou!