Having a HUGE (10GB+) Pagefile isn't going to make any difference than having say a 4-6GB Pagefile.
Plus as others have said, the Pagefile is NOT equal to RAM, it's more of a Cache in which the OS and Software can store data for later use, ergo making things appear faster.
It's best to just let Windows decide the appropriate Pagefile size, especially if you've got 4GB+ of Physical RAM.
P.S You can even disable the Pagefile to improve system performance but I wouldn't recommend it as it does cause some Software to fail.
You can also theoritcally have a Pagefile of up to 16 Terabytes if you really want to have a shit-load of Virtual Memory and a Computer so fast it bends time itself (using this kids logic)!