This setting optimizes the contiguous file allocation size for the file system and can be especially useful for disk intensive applications. Open up your registry and go to:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\FileSystem
Create a DWORD value named 'ConfigFileAllocSize' and set the value to '200' (in hex) or 512 (decimal)
Open a command prompt and type dir c:\ /w /s
This command forces Windows to run through and list every file on your hard drive. We're interested in the last statement it makes--the file totals. Divide the total number of bytes used by the total number of files, then divide that number by 1024 to get an average file size in kilobytes. This will give you an idea of what your particular system is using and needs, vs. some random generic setting.
To find a value for this registry entry, divide your average size by 32, round up to the next whole number, then multiply by 32 again. This will give you a number that's a little bigger than what you're currently using to provide a little safety net against future fragmentation.
OF course if you change this and then change your usage habits then you might get fragmentation in the future so change this with care.