cheap and dirty linux server build

what is the minimum spec linux server pc i could get away with?

Its just gonna be used for storing and streaming media.

I was thinking amd, 512mb ddr2 ram, cheap gigabyte board – need recommendations for a mainboard.

Do i go dual core considering there dirt cheap.

I have the HDD’s, think I got a cheap case in the loft. Will need a psu, so what would you recommend?

Was looking at installing debain on it.