The resolution of both modes is the same: 360 lines. Anamorphic will fill a widescreen TV though so I'd go that way.

I have tried both and didn't notice a quality difference. I was just wondering why they would give you the choice but it make sense that anamorphic fills and a wide screen tv.
Thats why these forums are great.

If you're using Vegas (and since you're on this forum you probably are) you can shoot 4:3 video and do the 16:9 crop and stretch in Vegas. It will the same and let you choose which part of the frame you want to use vertically. Progressive video tends to show more horizontal detail, and many people feel that 360 lines of progressive resolution is about the same level of detail as 480 frames of interlaced video. This is the case whether you use the camera's stretch mode or Vegas's. Both methods simple double every third line with progressive footage.

Actually with the DVX100 shooting progessive the vertical res goes up becuase they have to turn off line averaging. The down side is the noise goes up 6dB. Best solution for 16:9 is the anamorphic adaptor however if you're are using that you should get hold of the relevant correction and limitation charts that someone from www.dvxuser.com has kindly put together.
Bob.

By anamorphic adaptor, I assume you mean the lens attachment that optically compresses the image for anamorphic? Can you be a bit more specific about the info on dvxuser.com? I have the adaptor. I took a quick look on the pages, but I didn't find a topic that seemed to match what you were pointing out.

Thanks for any more details you can provide.

Here ya go:
http://www.dvxuser.com/articles/anaguide/
Like most 16:9 adaptors this one isn't perfect, I think the guide tells you how to compensate and what areas to avoid so things don't go out of focus.
They've also got DVD showing how various filters affect the image, actually one of the things that attracts me to the camera is that forum, a bit like Vegas. If it wasn't for the HDV stuff about to hit us I'd be buying a 100A.
Bob