...By Victor Frankenstein. No, just kidding. Since the question was asked, I'll go ahead and share the methods I used to mod my Windows desktop to look like OS X. Here's how I pulled it off:
Aqua Dock - This is the program I installed to mimic the OS X Dock. It's pretty smooth, even on my older computer. There are a lot of customizable options, too. It took me a while to find them...you have to right click on a space between icons. :-) Another alternative I found is RK Launcher. It definitely has a better website, but I didn't like the product as much. It felt too artificial.
UXTheme Patcher - This one was a mite confusing. In order to install one of these themes for XP, you have to first install their Patcher program, then download the themes, unzip then, then double click on one of the theme files. It will open the XP display properties where the theme will be available in the list. What this theme does is modify XP to look like OSX. In order to get the full effect, you'll have to move your taskbar to the top of the screen, then size it down to one line.
Wallpapers - These come with the UXThemes zip file.
Widgets - This one is easy. I used Google Desktop and just picked a few choice Gadgets to place on my desktop. You could also use the Yahoo Widget Engine, if you felt so inclined.
So...yeah, that's how I did it. Not too difficult, I just had to find the tools. So you should be able to do it pretty easily since there's no Googling involved. :-)