I believe one significant difference was the switch to a newer VIA Southbridge which has ATA/100 support. I have the original revision, which has ATA/66. It has been pretty satisfactory, although when I tried to install Mandrake 8.1 on it, it had a kernel panic related to the second CPU not syncing. I'm a Linux newbie so I don't know what to make of that... it has had fantastic stability in Win2k under very severe loads on both CPUs and the motherboard as a whole, so I think it's probably something a Linux guru could fix.
Groucho Marx: "Why, this is so simple, a four-year-old child could do it! Someone find me a four-year-old child!"
^ me with Linux