Dwarf

The Vista service that organises Page File useage is much more comprehensive and effective than that in previous versions of Windows. I recommend that you leave the settings alone and let the system manage them as it sees fit. The only change I would recommend is to place the Paging File on a separate drive if you have one available, otherwise I see no need to alter anything. As regards deleting the Paging File on shutdown, that is a setting which is beneficial for those who use their systems for confidential work. The vast majority of users don't fall in to this category, and indeed the default setting in the registry is for this deletion to be disabled. Check the following location to see what your current setting is.
Dwarf

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management]

'ClearPageFileAtShutdown' 0=disabled (default), 1=enabled