Windows XP with Vista Flip and Mac dock!
I have been reading this today and its bloody helpful, I now have a full mac theme, widgets and Vista Flip as well.
1 Remove all unused shortcuts and icons. Right click the desktop and go to "Arrange icons by" and uncheck “Show desktop icons”. You should now have a completely clean desktop. Don’t be afraid. You can still access the My Computer, My Documents, and Recycle Bin standbys from Windows Explorer.
2 Install RKLauncher (Even though Star Dock is better because you can get a mac OS X Leopard (10.5) theme). RKLauncher (also called RKDock) is a free Windows version of the animated Mac taskbar, or “dock.” You can download it here. RKLauncher comes with a pretty cool theme. If you want to make your dock look exactly like a Mac though, try RealDock for RKLaucher, a great clone of the Mac Dock appearance.
3 Hide the taskbar. It doesn't make sense to have both ObjectDock/RKDock and the Windows taskbar. Right click a blank space in ObjectDock, go to the settings tab, select behavior then on the box with check marks select “Hide the Windows Taskbar,” and hit OK. RKLauncher should work similarly. This makes the taskbar disappear. You can also just move the taskbar to the front of the screen.
4 Add Widgets. Widgets are desktop toys to entertain and to inform. Think of them like things you’d put on a real desk: a picture frame, a newspaper to a dancing hula girl! But they’re on your PC desktop, not your real desk. You’ll get it once you see it. They could be a fun addition to your boring computer. Download free widgets from the Yahoo Widgets page. You'll download a widget machine called Yahoo! Widget Engine, which comes with widgets like a picture frame, analog clock, calendar, and weather display. You can get more widgets like RSS news feeds and a dancing hula girl from the widgets gallery. Yahoo! has also released an engine that can help you make your own widgets and is available here.
5 Change your wallpaper to look like Mac OS X Leopard or Snow Leopard. Or you can get a high resolution wallpaper here which won't make your computer mimic a mac desktop but will add a sense of style and a unique touch.
6 Install WinFlip, you can customise the keys for it to anything you want but it is defaulted to Windows Key and Tab, it is a free download here
7 Move your buttons. ShellWM is a “titlebar-only” shell replacer. It lets you have the maximize, minimize and close buttons on the left for free. You’ll want to download this theme.
8 Change your mouse pointers. Install this neat little program and it does it for you, found here
9 Get KeyVolume: Adjust Volume Quickly (Shortcuts) Try the app KeyVolume. This will allow you to adjust your volume with shortcuts using your NUMPAD like ALT & +, ALT & -, and ALT & *. This app makes volume adjustments look just like on a Mac. If you don't have a keyboard with volume controls you should give it a try.
Modified from: http://www.wikihow.com/Pimp-Your-Window ... ac-Desktop
This is my current desktop: