Bad Artifacts with 720p Video rendered to DVD

I have a Vegas (10.0d) project that contains some AVCHD files (Panasonic HMC40) shot at 720p. The subject matter is football. Some of the video was shot up high in a stadium. In that video the lines of the football field, the track and bleachers in the background are really showing some bad artifacts (I think that's what you call it). Other football video I shot on a grass field at ground level looks pretty good. Obviously the harsher lines of the bleachers and artificial turf field are showing up much worse than the softer video shot on grass field with no bleachers in the background, etc.

My question: Is there anything I can do to this video to get rid of this issue and make it look better? Should I render the clips in another format and then bring them back into the Vegas project and re-render the MPEG2?

The Vegas project setting are for 1280 x 720, 59.94p. The rendering template is the DVD Architect NTSC Widescreen. I am rendering for DVD using Main Concept MPEG2 with a bitrate of 8,000,000 6,000,000 2,000,000 2 pass with the video rendering quality set at "Best".

Help would be much appreciated.

Thanks
Dave P.

Intel I7 950, 12GB RAM, NVIDIA GeForce GTX 460 SE, Vegas Pro 10 (32bit/64bit), Windows 7 Pro 64bit, LG WH10LS30 10X Bluray Burner.