There is a large amount of data that is consistently sent back and forth between the headset, tracker, controls, and PC so a hefty PC is required to keep up.
The PC minimum requirements for use with the Rift are as follows.
NVIDIA GTX 970 / AMD 290 equivalent or greater
Intel i5-4590 equivalent or greater
Compatible HDMI 1.3 video output
2x USB 3.0 ports
Windows 7 SP1 or newer
You will want to run a simple test to ensure your PC is “Rift Ready” by running a test that can be found here.
If you are not comfortable with building your own PC. Dell and Alienware computer manufacturers have announced their commitment to virtual reality. They are making Rift Ready PC’s that come bundled with an Oculus Rift starting at $1500. These can found on both BestBuy’s and Amazon’s website.