I have the KT7. It only supports ATA/66. You need the extra drive connector on the KT7-RAID to get ATA/100. On the other hand, no drives currently reach the promise of ATA/66, never mind ATA/100
In addition to ATA/100, the KT7-RAID supports RAID 0, RAID 1, RAID 0+1. RAID 0 is disk striping, (I think), which has huge performance advantages over a single drive (but I didn't need it). The KT-RAID can support up to 8 drives. The KT7 can only support 4.
Those are the only differences that I recall except the KT7 is rumored to have fewer problems due to not having the RAID controller.
I love this board. Jumperless is the way to go. I have never had an easier motherboard installation.
I had only one problem. I attempted to overclock my 1000 Mhz Duron to 1100 Mhz. Dumb, It was pretested to 1000 Mhz and I should have known that if it could go higher it would have been certified higher. The system not only failed but refused to boot afterwords. After a few minutes of panic I reset the CMOS (so it wasn't quite jumperless for me). Fortunately, everything was back to normal.. I later learned that after shutting down the system, after a BIOS boot failure, all you have to do is kill the power at the power supply (via the rear switch or pulling the cord). The BIOS will revert to a default setting.
In your case, the only advantage I could see in getting the RAID board would be furture expansion of IDE devices.
1. You shouldn't put slower IDE devices on the the same connector as you hard drive.
2. Let's say you have a DVD/CD drive and a CD-RW on the second IDE connector and your hard drive on the first.
3. Then you want to get an IDE ZIP drive. At that point you'd be forced to either make one of these slower drives a secondary to the hard drive and take a performance hit, or you'll have to be an add-in IDE card.
That may be stretching it a bit, but I thought I'd mention it.