Dave, I've never done any MySpace layouts or even looked at many for that matter. After reading your post though, I did look around a bit. Here's what I found. Most of the
free stuff is garbage, but there are some people doing some nice-looking MySpace layouts. Here are some links for you that I hope may help you out.
MySpace Layouts at CreateBlog -- this website has some of the more sophisticated and better-looking free designs I've seen for MySpace.
MySpace Skins -- this site also has some nice designs and it also has a some tools including a MySpace Profile Generator that might help you build your own profile or modify an existing one for your needs.
Hacking a More Tasteful MySpace -- this is a blog article by Mike Davidson. Mike is a well-known designer in Seattle that has done some big time projects, including the ESPN website. The article has quite a bit of info on developing good-looking MySpace layouts.
As for the layouts themselves, I took a look at the source code for five or six basic/standard MySpace layouts this morning and found that, at least the ones I looked at, were pretty simple really in terms of what it would take to modify them. Those had only two or three text colors, a few font-family references and three images (background, header, contact). After that there would be maybe some border tweaking and such that you might want to do.
The sites above have some pretty fancy layouts. Customizing some of those would probably take a fair amount more work. It seems to me that as far as doing a basic/standard MySpace layout goes though, the place to start would probably be to find a great background image you like. You might be able to use a portion of it to develop the header and contact images or just go with something else for those images. Once you get your images, then it would probably just be a matter of sampling some color from them to use for text and border colors.
I hope you find some of this helpful and good luck with your design.