Well, I have a Yamaha F1 44/24/44 CDRW drive and a TDK 420N DVD+R/+RW drive and I have them both hooked up. The reason for this is two reasons:
1. The DVD burner only has 12X writing for CDR vs. 44X on the Yamaha.
2. I don't want to put unecessary wear on the DVD burner when I have a dedicated CDR burner..
It's all a matter of preference I guess.. This was just my preference..
I also put a DVD reader and DVD Burner on the same ribbon since I would never do copies on the fly. Why? Because most DVD movies are DVD-9, and the DVDR medias are only DVD-5 so you couldn't do a copy right away anyways. You would first have to rip the DVD to HDD using some type of shrinker such as DVDShrink. That's how I backup my DVDs...