Ultimate guide to desktop customization: Install a Linux distro with GNOME, install Compiz Fusion.

I have a few customizations on my laptop, but very few, to keep it simple to use, looking nice, and to not kill the poor thing (Pentium M 1.6 GHz with 2 GB of DDR RAM, ATi Mobility Radeon 7500 32 MB VRAM). Rocketdock with custom-made icons, and a modified Royale theme.

My desktop PC is completely uncustomized, except the desktop has no icons, and I just use the start menu instead.