To meet the recommended PC specification, you'll need the following:
Windows 7/Vista/XP PC (32 or 64 bit)
Processor: Quad-core Intel or AMD CPU
4 GB System RAM
6 GB free HDD space
DirectX 9 compatible NVIDIA or AMD ATI video card with 1GB of RAM (Nvidia GeForce GTX 260 or higher; ATI Radeon 4890 or higher).
DirectX compatible sound card
Internet access for Steam activation
And here's the minimum requirements to get the game up and running:
Windows 7/Vista/XP PC (32 or 64 bit)
Processor: Dual Core 2.0 GHz or equivalent processor
2 GB System RAM
6 GB free HDD Space
Direct X 9 compliant video card with 512 MB of RAM
DirectX compatible sound card
Internet access for Steam activation