I've used Vegas with DVCPro (which is better then DV) and didn't notice a lower quality at all. Rendered out, etc. You must have a rendering setting changed from a template somewhere. Use the NTSC DV template, that should work. Try playing the AVI on his computer too. Maybe it's your video card.

There is a difference in PC and Mac gamma settings. So an image created on a Mac can and likely will look darker on a PC screen. Conversely a image created on a PC, can and frequently will look pale on the Mac. A correctly calibrated TV will have a gamma of about 2.2. While a Mac has about 1.8 and a PC will have about 2.5.

See where I'm going yet?

Remember with TV and computers the image's hue is made from three primary colors. Red, Green and Blue. If you look at any color patch that allows adjustment of hue in any computer graphic application including Vegas you'll see the values of each primary color can range from 0 to 255 with the higher value producing the most intense shade. Varations of the three primary colors produce all in-between hues. What you may not know is varations in gamma result in a hue shift.

In Caucasians, especially the red component mostly in highlights and to a lessor extent the mid range and shadows in skin tones can be shifted to the red on one platform and to the blue on the other. So a good looking skintone created on a Mac because of the difference in gamma can result is a cooked lobster look if brought into a PC platform graphic program. Same image looking right created on a PC brought into a Mac can look blueish, like the person was in the deep freeze.

Another reason to view on an external monitor that if setup correctly has a gamma somewhere between the gamma settings of a Mac and PC computer monitor.