Another PC dude here!
Intel's new Core Duo 6400, OC'ed to 3.1ghz with 2GB RAM, 150 GB primary drive for OS and program files; RAID 1 via 2x 300 gb drive for daily work storage for clients; 1 terabyte of drives networked for backup. I'm lazy in some ways that I find backing up onto double layer DVDs a pain.... gotta get into the habit of burning discs.
Display wise, I'm currenty viewing my stuff on an ol' LaCie 19" ElectronIV Blue. Probably upgrading to a 30" Apple cinema display in the coming weeks/months.
My main business is commercial photography and print concept/design. Normally have Photoshop, Capture One Pro, QuarkXpress or InDesign (depending on project/client), and some web tools such as Dreamweaver and Flash running.
Might hop over to Mac as I'm really fed up with Windows and the daily security updates, and all malware/viruses around. Before being a photographer/designer I was a web developer building front/backends on Windows servers..... hence always used to that OS
Cheers!