If you are talking about the Calendar, To Do and Events, its a program called Rainlendar. http://www.ipi.fi/~rainy/index.php?pn=projects&project=rainlendar
Right-click on the desktop. Select Properties. Click the Appearance tab. From the "Windows and buttons:" drop-down box, Select "Windows XP Style." From the "Sub Design:" drop down box, select "Olive Green." Click "Apply". Voilá! You got nasty avocado green (but shiny) windows.
Wow, I feel like an idiot. That easy, dang. I went with the silver, that green looks terrible while visiting the bbs in dark version