Check AutoCAD 2014 System Requirements
If your work is mostly or entirely 2D — and therefore, this applies especially for LT users — AutoCAD 2014 runs adequately on pretty much any recent computer that runs Windows 8, 7, or XP. On the other hand, if you get heavily into 3D and photorealistic renderings, then there is no such thing as "too much."
AutoCAD 2014 does not run on any version of Windows earlier than XP (Home or Professional). Autodesk also does not support you if you have AutoCAD 2014 running on Windows Vista.
There are 64-bit versions of AutoCAD 2014 and AutoCAD LT 2014 that run in the 64-bit versions of Windows XP, 7, or 8. The 64-bit versions can access much more system memory for faster operation, while 32-bit systems are limited to 2GB or 3GB of RAM. This is normally significant only if you get into heavy-duty 3D work.
Application compatibility: If you use third-party applications with a previous AutoCAD release, they may not work with AutoCAD 2014. AutoCAD applications developed with the .NET or the ObjectARX (AutoCAD Runtime eXtension) interfaces may or may not need to be recompiled. Many LSP (AutoLISP) programs written for the last several versions of AutoCAD should work without change.
Built-in support for VBA (Visual Basic for Applications, a Microsoft programming language) isn't included in AutoCAD 2014. You can continue to run VBA applications, but you first have to download and install the VBA installer from the Autodesk website. Go to www.autodesk.com and enter VBA installer in the Search box to find it. There are 32- and 64-bit versions, so make sure you download the right one for your system.
Computer system requirements: For the latest on specific requirements and recommendations, go to http://usa.autodesk.com/autocad/system-requirements. Note that there are few "absolute" requirements. A beginning student or an occasional 2D user can often get by with somewhat less than the "recommended minimum," but at the other end of the scale, if you're doing daily work on very large, complex 3D models and are producing photorealistic renderings with shadows, reflections, transparency, and refraction, then there is no such thing as "too much" hardware. In any case, you can never have too much RAM.
You should also note that a gaming graphics card is different from an engineering graphics card. It's well worth the few extra dollars to get an engineering card, especially when working in 3D. So how can you tell the difference? First, check the price. Engineering boards will usually be a little more expensive, but not outrageously so. Next, make sure it supports "Open GL" and/or "Direct 3D."