For my own personal workstation, I use a Windows PC running a few different applications that assist me with whatever projects I have either at work, at school, or any projects I wish to undertake.

Desktop Workstation
ASUS M4A785-M AMD 785G Socket AM3 Motherboard
AMD Athlon II X4 620 2.6Ghz AM3 CPU
3x Centon 1024MB PC6400 DDR2 800MHz
Visiontek Radeon HD 4850 1GB PCIe w/Dual Link DVI
LG 22X DVDRW SATA OEM
Logitech MX 5500 Revolution Keyboard and Mouse
5.1 Surround Sound Speakers – Logitech
500 GB Hard Drive
1.5 TB External Drive

Common Applications
Microsoft Windows 7 Home Premium
Microsoft Office 2007
Mozilla Firefox
Winamp
Steam (I play games)
Avast
Malwarebytes
Pandora (via Adobe AIR)
Filezilla
Notepad++