You can disable the screensaver for the duration of a program using this. Supply the normal command line for the app as the arguments to this. To test it, set your screensaver timeout to 1 minute and run a command like:

noss perl -le"sleep(1), print for 1 .. 61"
[download]

noss.pl:

#! perl -slw
use strict;
use Win32::API::Prototype;

ApiLink(
    'user32',
    q[ BOOL SystemParametersInfo( 
        UINT uiAction, UINT uiParam, PVOID pvParam, UINT fWinIni 
       )
    ]
) or die $^E;

SystemParametersInfo( 0x0011, 0, 0, 0 ) or die $^E; ## SS off
system @ARGV;
SystemParametersInfo( 0x0011, 1, 0, 0 ) or die $^E; ## SS on
[download]