I know that I have gotten a few e-mails regarding the sizing of Swap Files. I think there is a problem that many people have -- they don't really understand what the swap file is and what it's used for.
So, I am going to explain what exactly the swap file is and point you to a page on the Microsoft site that gives a detailed breakdown of virtual memory and how the operating system manages it.
Your servers use their memory to run processes. But, there are times when your system will require more than the available memory. At this time, it writes the lower priority processes to disk. It does this by paging them, in 4K chucks, using the swap file.
This is where the "Paging" file gets its name. It is swapping processes in and out of real memory.
The Virtual Memory Manager (VMM) is what the operating system uses to manage this process. The VMM runs in protected space, along with the Kernel.
To be honest, I am probably botching this explanation, so I will just provide a link to the MSDN page for you to view.
If you have any questions about your Paging file or your Swap file, drop me a line.