I'm looking to modify the background color, highlight colour and the font for both viewed and non-viewed items in the start bar and programs panel, and everything else, like control panel, for the classic start menu... for windows XP pro
I think the classic Start Menu color is simply the "buttons" or "menu" colors. I forget which. It's likely that it's based on one of the common colors, so if you change it, it'll change the color in a lot of other places.
Getting the colors right for non-skinned items can be a bit of a pain. Especially when applications use their own colors mixed with system colors.
I dunno about everything else, but I get the feeling you want to change some things that can't be changed.
Skin Studio 6 has a whole section on XP specific stuff. XP control panel stuff is there.