How can I configure my USB keyboard to a different lenguaje than my integrated keyboard's lenguaje?

Hi

My MacBook Pro is in Spanish, but I just bought an USB keyboard in USA and the keys do not match, because all my system is configured in Spanish. Is there any way to let OSX know this and thus have different layouts for each keyboard? Lets say Spanish for integrated and English for USB? Is really annoying not being able to write some characters with the USB keyboard because of some keys are "missing" on it (longer left Shift key instead of a small one and 2 extra key for "<" and ">" ), the "(" and ")" are also misplaced, and so on...