HHD case to USB

[Hellfighter]

ran into a bet of trouble
no room in the tower for another Hard drive

i have SATA 1T Hard drive, i recall one can encase them into a housing to use as a External Hard drive

but i need help to find this case to house the Hard drive into to plug it into a USB port
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btw; Ram card need a bet help in detail
my new tower has 2ea DDR 1024mb ram card 800mhz
am i thinking this will work link: http://www.amazon.com/PNY-OPTIMA-PC2...+1024mb+800mhz

don't know about the "PC-2 6400"?