xset command setting not sticking

[Tech Geek]

Hi,

I am using Debian Lenny on x86 machine. I need to make the following command
permanent upon every boot:

xset s off -dpms

I am booting into GNOME with GDM.

I have tried adding this to my /home/user/.xinitrc file:
#!/bin/bash
xset s off -dpms

and made it executable:
chmod +x .xinitrc

but it is not able to retain the setting.

Thanks.