Dawnguard is the first DLC for The Elder Scrolls V. According to the Bethesda, this DLC pack is going to be released for the Xbox 360 on this summer (PC and Playstation 3 versions are expected to be released after the Xbox 360 version) and more information about this DLC pack is going to be on E3.
The Elder Scrolls V: Dawnguard System Requirements
PC System Analysis For The Elder Scrolls V: Dawnguard Requirements
Your PC will need a graphics card thats as powerful as a GeForce GTX 260/Radeon HD 4890 and it should be paired with either a Phenom II X4 940/Core 2 Quad Q9400 2.66GHz CPU to match the The Elder Scrolls V: Dawnguard recommended system specs. This PC setup will deliver 60 Frames Per Second on High graphics settings on 1080p monitor resolution. System memory required for The Elder Scrolls V: Dawnguard is 4 GB performance memory. You should also have 1 GB system memory for min specs. Make sure your GPU can run DirectX 9 or The Elder Scrolls V: Dawnguard won’t run. Recommended needs around a 12 year old PC to run.