No probs, it should do the trick
The IDE (Integrated Drive Electronics) channels are just the two sockets on your motherboard where the flat ribbon cables plug in. As for PIO Mode - it's a slower transfer rate than UDMA mode, so if your burner is running in PIO mode, speeds will drop and you may get failed burns.
Even if you only have the one burner installed, often your hard drive(s) are connected to your Primary IDE cable, so the secondary one is often used for extra hard drives or burners etc. A lot of motherboards have two IDE channels.
As for what caused your drive to drop into PIO mode, it could have been anything from reading a dodgy disc (if Windows encounters x amount of read errors on a disc, it'll drop the transfer rate til eventually you're left with the dreaded PIO Mode) to a dodgy IDE (flat) cable connecting your burner. I'd say it's more than likely that it had problems reading a disc and thus dropped the transfer rate.
These are really basic explanations, as I'm crap at explaining things - maybe you'll get a more in-depth explanbation, though