I guess you got 32bit....
/Moved to general
ehm go to start > Configurations > System and read ur specs
if it aint saying 64x u got 32-bit
u can also check this with
Win button + R button > dxdiag > ok read specs there.
done if not wel fak that i get a cab.
go on desktop right click properties/settings and it should say down there Color quality and here u go
shoudln't you know what BIT your comp is :P, Mines Win7 64Bit Intel Core Processor ( Quad ) But Lol why do you need to know ?