Generate files of a specific size
This handy utility allows the instant creation of files of a specified size.
http://technet.microsoft.com/en-us/sysinternals/bb897428.aspx
Command:
contig -n [drive letter]:\path\filemname.tmp [size in bytes]
Example
contig -n C:\Users\paulw2\Downloads\25GBfile.tmp 26843545600
Use with caution, it is instant!