I just received a new Dimension M6300 and although it has a hidden restore partition on the hard drive, it does not present the "Dell Factory Restore" option as described here.
After booting the M6300, pressing F8, and choosing "Repair Your Computer", the dialog presented is missing the last option "Dell Factory Restore".
The documentation specifically states that the Dimension laptop series support this option, and the recovery partition seems to be present.
I don't think F8 is for the Dell Symantec system restore utilty. Check your manual for the exact procedure. Don't know about your computer but mine is CTRL F11 keys.