Vista/7 Navigation Button Colorizer is a tool which can easily change your Windows 7 & Vista’s explorer navigation button colour in one click. The app now seems to have been updated to run on Windows 7 too!
While I have not tried it, Windows 7 & Vista users may want to check it out on DeviantArt.
PS: Your anti virus might just report it as malware – its a false positive says the developer. My NOD32 did not identify it as malware.
Now works on Windows 7 & Vista.