How to configure PAE in Windows 7 32bit?

My Friend buy CoreI7 Processor and Gigabyte Motherboard with 8GB Installed RAM in Windows 7 Operating System 32Bit. but the system properties sheet tell only 3.9GB available Memory.. I’ve done some research on how to maximize 8gb of memory to run on Windows 7 32bit OS and PAE come in first. i don’t have any idea if this work or what I will do.. Please guide me if someone has done enabling PAE and what parameter i will use to successfully Force enable the PAE to use all of 8GB Memory