I'm relatively new to this game and have just done a friends wedding.
I want to put it onto DVD ( about 50 mins avi) and I'm using U-lead Video Studio 7. Which would be the best option for compression MPEG - 4 Video Codec V1/V2 or V3 or DV Video Encoder Type 1 or type 2? I want to keep the quality as best as possible.

you'll have to compress it to MPEG-2 if you want to author a DVD-Video, but don't worry, since you've only got 50 mins of material, the quality will be great (you can set the VBR somewhere between 6,000 and 8,000 kbps) it will look just fine.