Well, you've already seen what gear David, Cameron, Eric, and Liam use. I suppose now it's my turn - though, a disclaimer: I like to keep things very streamlined. The less clutter (physical and digital) I have, the better. While I may not have as much stuff as them, the things I do use, I use more.
There's no denying that my desktop is dated, but it's capable enough for my needs. It's a self-built PC with an Intel Core i5 750 CPU overclocked to 3.4 GHz, 4GB of RAM, a 1TB HDD, Radeon HD 6850, Sound Blaster X-Fi, and old Creative 5.1 speakers, coupled to two 22" monitors.