Hi Higgy,
Unfortunately DVD camcorders aren't generally as good quality as DV tape camcorders, because they compress the video a lot more, but you might be able to rescue it.
If you're only doing occasional video editing, I reckon Adobe Premiere Elements would be a good program for you to use. I think you can download a trial version from
www.adobe.com, so give that a go and see what you can do with the brightness and contrast.
Let us know how you get on!