I agree with computerxpds. Windows does a good job of managing the paging file, and most users would find little practical difference, unless the fixed paging file can be on a fast dedicated drive.
The biggest optimization by far is minimising the requirement for paging, which is to say adequate RAM. If a system with 3GB of RAM is using the paging file enough to cause performance issues, that tells me the system usage is heavy enough to warrant using a 64 bit OS with more than 4GB of RAM. But if you're lucky enough to have a Windows installation that can access beyond 3GB of real memory, then having 4GB of RAM fitted could give more benefit from the extra 200MB or so of available RAM than you'd get from tweaking the paging file.
Pleased to have been a Microsoft MVP (Windows Desktop Experience) 2007/8, 2008/9
I pressed F5, and I'm feeling refreshed...