What You Need
1. Grab a Lian Li Case. We've searched far and wide and it seems only Taiwanese manufacturer Lian Li knows how to build a sleek and functional PC with similar aesthetic points of a Mac. Silverstone and Antec get points for trying, but they don't even come close. The Lian Li featured above is the V1200 case. Obviously, you'll need to plug in all the parts to get it up and booting - we'll reserve this for another talk and assume you know how to piece together a power supply and a motherboard. Otherwise, consult our build-it article here.
2. Get Vista/Windows 7. The main reason being is that Windows XP doesn't have drop shadows and requires tons of additional software to get the Mac OSX look. Plus, why are you still on that 10+ year-old OS, grandma?
3. Install iTunes. A no brainer here. If you want the Apple multimedia experience, you're going to need iTunes.
4. Install RKLauncher. This program pretty much emulates the OSX dock perfectly. It even has that cool minimizing genie effect that we all know and love. Works best with Vista. Compatible with Windows 7.
6. Move that taskbar up, dock to the bottom. Right click to enable resizing of the taskbar and drag it to the top of your screen. Though this may not emulates the OSX menu bar exactly, it certainly is a convincing look. Launch RKLauncher, make sure its location is at the bottom, and have it run every time windows starts. Customize it using all those pretty icons you've downloaded.
7. Wallpapers matter. While Windows 7 does include a few nifty ones, if you're really trying to match that Apple look, you'll need something that screams "sleek." Hongkiat has a great roundup of 60 Mac wallpapers over here.
8. Get crazy! We're not too big on adding customizable skins all over the place since it'll start eating up your RAM eventually, but you want to go all out, check out Instructable's hardcore conversion instructions (lots of programs, lots of skins).