Campbell, you need to be aware that, compared to newer machines, your computer is quite slow which means long render times.
I looked up your camera and it shoots either 1920 x 1080 50p or 50i.
My guess is that you have it set to 50p which is why you’re experiencing some of your problems when rendering to DVD.
It’s OK to match project properties but there is one “gotcha” to be aware of and that’s the “blend” vs. “interpolate” setting.
John Rofrano does an excellent job of explaining this in the Jittery footage (field flicker?) thread.
Follow his advice and you should be ok.
The other issue is rendering for DVD.
As I said earlier, you have to render your video to MPEG-2 and your audio to AC-3. Give both files the same name and put them in the same folder. That way, when you launch DVD Architect, load the video file and the audio will automatically follow.
Render using the MainConcept DVD Architect PAL Widescreen video stream template. Use the default settings for now.
Using a bitrate calculator to optimize render settings has been discussed at length on the other Cow Vegas forum so do a search there for more info.