blue and white power use

hi, im putting in myt car, i wanted to know, how much power is required, for the board, a full size dvd-rom and 3.5 inch hard drive,

do you think a 200 W power supply should work?

even this one?
http://www.mini-box.com/s.nl/sc.8/category.13/it.A/id.300/.f

im going to use an ATX extender cable and clip the one wire that needs clipping

i hope this will work, because its small and silent (and cheap!)

thanks!

eric