The chat client is Adium, and the entire visual element of it is editable, so I just adjusted it until I liked it.
The icons are just super big.
The icon sets are called 'Litho System' and 'Litho Extras Vol. 1 - 7'
I used a program called Candybar to set up all my icons, and another program I can't remember at the moment to delete all the shiny things and glowing orbs on my dock. But you can also do that stuff on your own, I just got lazy and did it with this program.
As for the wallpaper, I'm not sure exactly where I got it, but I think I just googled 'faded wallpaper' or something.
Think while it's still legal.