try DVD Creator, I always use this tool, it works fine. you can input the avi files and output as ISO. it's easy.
http://www.leawo.com/dvd-creator/
Thank you, I found one I'm going to use. I should have mentioned that I only need to convert one .avi to DVD. This is why I was looking for a lightweight program, I didn't want something that was going to leave a big footprint since I probably wouldn't be using it that often, if at all.
I've heard of DVD Creator, is this a full-fledged DVD manipulation program? Meaning, does it rip and burn to disc in lieu of creating the ISOs? I download most of my software so I'm constantly burning DVDs. I used to use Cyberlink and then Nero but when I installed Windows Server 2008 R2 I had to switch to yet another program because Nero doesn't support Windows Server. Now I use ImgBurn and I love it.