Excel 2007 : Formula to change text color based on value?

Given cell A1 = 10, how would I construct a formula that says: if Cell A1>5, then make it *red*, but if cell A1<5, then keep it black?

e/ and also, how do I create a formula that basically says, if cell A3 has the words "a, b, c" then "x", OR if cell A3 has the words "d, e, f" then "y"?

Thanks