Thanks for posting the differences. Here is an assessment based on my own needs:
SATA2 - 300Gbps vs 150Gbps. I know that there are no SATA2 drives yet, and SATA1 doesn't yet hit it's maximum bandwidth.
As you say, no such SATA drives yet. I have not heard anything about future availability dates of SATA2 drives.
Up to 8 SATA drives can be supported.
SOLTEK SL-K890Pro-939 supports 4 SATA drives using two different SATA controllers (2 each). That is plenty for someone building a quiet system.
SATA and PATA drives can be mixed in RAID. This one seems usable to me now, as I have one of each.
I am building new, so not an issue for me.
More RAID variations available - RAID 0+1 (this may be available with other chipsets), RAID 5 (on some boards). Don't know what either of those are.
It appears that SOLTEK SL-K890Pro-939 supports RAID 0, 1, 0 + 1 in only one its two SATA controllers (supports 0, 1 in the other). Hmmm, I thought that RAID 0 + 1 needs a minimum of 4 drives (http://www.sohoconsult.ch/raid/raid0+1.html
10 USB ports supported (versus 8 on with VIA and ATI chipsets)
SOLTEK SL-K890Pro-939 supports 8, which is enough for me.
ActiveArmor - NForce's hardware-based firewall with lower CPU utilization then software firewalls. I'd sure like to see an evaluation of this one.
I would too.
At least one Gigabit Ethernet port. Many boards have two.
SOLTEK SL-K890Pro-939 has one Gigabit Ethernet port.
Nforce4 boards seem to be more likely to be high overclockers.
Since I am building a quiet PC, and heat is the enemy of quiet, not an issue for me.
Right now I am looking at the SOLTEK SL-K890Pro-939 with VIA chipset and the GIGABYTE GA-K8N Ultra-9 with NVIDIA nForce4 chipset, because both have passive chipset cooling (I believe). But it appears that the VIA chipset will run a bit cooler.
But I am still waiting on availability of the PCI Express GV-NX66T128VP (NVIDIA GeForce 6600GT) with passive heatpipe, and also the new Antec cases (probably Sonata II).