Only you can know how large your pagefile should be. The x2 rule is an abomination from a day of tiny amounts of RAM and high RAM cost which should have died a long time ago. If you truly, TRULY want to know, then you will need to run some performance counters in the background for a week of typical use, then see what your peak RAM usage was during that time.
That is how much RAM you need total. If you don't have that much RAM then make it up with pagefile, that's what the pagefile is for, giving you the total RAM required. The problem is that people treat the pagefile as something different, when all it is is harddrive RAM. The idea of having a larger pagefile just becaused you increased the amount of RAM in your machine is like a bad joke, but one too many believe. Imagine beliving 2GB of RAM was more than enough for your machine, then buying an extra 4GB and shoving that in to. That's what the x2 rule is: retarded.