Hi, my brother asked me to recommend a good AVI to MP4 converter program to him and although I've been using Allok Video Converter for the past 2 years it sometimes gives me out-of-sync issues.  I'm wondering if anyone here could recommend something that you like and have had very few issues or no issues with.  Freeware would be preferable but shareware or retail would be ok as well.  Thanks!

I usually use SUPER to convert everything, pretty universal software and free too.
Also I sometimes use xvid4psp to convert videos to watch on my cellphone.

http://www.convertavitomp4.com/
Free and very easy. Tiny download (size of a song). Never had a problem.

FormatFactory..its the best converter out there.

+1
Format Factory hands on ! Easiest, faster converter, lots of possibilities, you can extract whatever format from a video. I use it to convert .flv into .mp3.

I use winavi all in one:
http://all-in-one-converter.winavi.com/

xvid4psp, I know it's already mentioned here, but for specifically MPEG4 it is incredibly good.

http://www.mediacoderhq.com/

The only video converter to actually encode in 10-bit depth for H.264 (HD) on the MP4 container, which gives you higher quality color and depth.

http://www.convertpdftoepub.net/  this one have a try! it's good

Do yourself a favour and re-encode that with AppGeeker or similar to convert .avi to .mp4 file - that's my opinion.