This is my Windows XP desktop. I dual boot with Ubuntu Linux but thats another story. And yes, that IS Windows XP. I downloaded and installed Flyakite OSX for the shell icons, cursors, and background. The Dock is RK Launcher which comes with Flyakite OSX, and the Finder is ObjectDock Enhanced with an Aqua skin. I use WindowBlinds Enhanced with an Aqua theme for the window themes / titlebar buttons / etc. I got the Dock icons at various places, some of them came with YzDock (which I was using before RK) and some came with RK, some came from the internet and some of them even came from a pack I downloaded for Ubuntu. As far as Dock icons go, just download YzDock and get RK Launcher with Flyakite OSX and you should have plenty of icons. I also use an app called iEx which is an Expose' clone, it works pretty well, just dont hold F9 for more than a second
Finally, the widgets are Yahoo! Widget Engine (aka Konfabulator.)
So anyways, thats my home away from home on my laptop. Windows XP is okay but it's ugly by nature and (IMO) it looks way too plastic. Aqua looks 'solid' and 'made for useability,' and I couldn't live without the Dock and iEx.
NOTE: Updated the image June 2nd, it looks a little more OS X-like now