customizing progressbar colors in win7

hey there --

I'm starting to get awfully tired of the green progress bars in Windows 7, but I can't seem to find a setting to change the color. I've done some searching, but all that I've found seems to involve installing a new theme file, which I don't want to do - I've already got a theme file that I'm perfectly happy with. I'll modify it if need be, but I don't know how to do that, and I don't know what tools I'd need to use anyway.

If there's a registry tweak or an easy way to do this, then I can do it that way, but I just don't want to completely overwrite my existing theme files.

Any ideas how I can make that one little bitty change?

what I am using I changed so long ago, I no longer have any idea what it is :) It's not the default Aero theme, though; as I said in my OP, it's a .msstyles file with some minor tweaks (red start bar, black windows, etc).

If you can do what you say, then great; just please give directions as well, as I don't know what to do with the the resources that you'll provide.

unfortunately I don't recall what I used to change the .msstyles file. I am pretty sure I just downloaded a replacement file that I liked from somewhere, instead of editing my own file to my liking (I didn't know that could be done, at the time).

What programs would you recommend to edit the file, and where might I get them?