Whenever you build a new server or workstation Windows automatically sets the pagefile size based on the amount of RAM available. Usually, it sets the minimum amount of RAM to 1.5X RAM and the maximum to 2X RAM. So, for a server with 2GB RAM the pagefile minimum might be 3072MB and the maximum size might be 4096MB.
That might work well for your base build, but what about after you add the applications you built the server to do? The pagefile requirements change dramatically after you install SQL, Exchange, antivirus, etc.
You can view the pagefile settings by checking your system settings (Right-click Computer Properties Advanced tab Performance settings Advanced Change). Take a look at the Recommended setting, as in the example in this article.
I recommend setting the Initial size to the Recommended size (4509MB in the example above), and the Maximum size to 2x RAM (8096MB for this server). This will have a truly awesome affect on server performance! I especially find big performance gains in Exchange and SQL.
It's interesting to note that even though Windows recommends 4509MB for a pagefile, the system's currently allocated pagefile size is only the inital size. You would think that Windows would adjust the pagefile up to the maximum size of 4096MB, but it doesn't.
I recommend taking a look at your pagefile settings after installing your applications and occasionally (maybe every 6 months) while in production and adjust as needed.