you need a minimum of 16gb to install W7 on a drive.
(personal work experience)
i install to a 16 ssd and windows warned me it was too small (installed anywhy) on boot the pagefile was disabled
i tried to install to a 8gb ssd and W7 flat out told me no.
installed to a 32gb ssd and W7 filled the pagefile to match my memory (8gb) and could install a few small apps. and office.