Two DVD-drives - audio out of sync with one of them


I live in region 2, but I’d like to be able to watch movies from R1 as well. I don’t want to try the free region firmwares, so I decided to install another DVD-ROM drive in my computer. I had one laying around useless anyways. I switched the second DVD-ROM into R1. It now plays R1-DVD’s, but there are two problems: 1) the picture stutters a bit once in a while and 2) the audio is out of sync. I can live with problem #1, but #2 is too much. What is causing the out of sync? Should the R1 drive be connected to the audio card like the one I alread had installed? Is there a special cable for this? I use Nero Showtime to watch DVD’s.