I have the KT7-RAID, and I think it's great.
The HPT370 Raid controller enables three (actually four) things on your mobo.
1. Raid capability
2. ATA-100 operation (meaning 100mb/sec data transfer rate...no drive can reach that right now, but its coming, so why not be capable?)
3. Two extra IDE channels
(1)I'm not using RAID, (2) but I am using the ATA-100 controller portion of the HPT370. This ensures that every bit of info gets moved as quickly as possbile. It's always best to put any hard drives on the fastest channels you can. (3) By putting my HD on the 370 channels, it lets my two CDR's each have their own master channel, instead of having one as master and the other as slave, which is what you'd have to do if you had your hard drive on the IDE primary/master channel, instead of on the 370 controller. See what I mean about "extra channels"?
If you only have one CDR, you won't hurt anything by not using the HPT370 controller, but down the line if you get another CDR, you'll have to reroute cables which is always a pain in the butt, as well as reconfigure your BIOS. I'd use the 370. You paid for it, it would benefit your other devices, and it's a faster means of transmitting data. Cheers.