Just buy the CX500 if you don't want to deal with the hassle of the $10 rebate for the XFX TS 550.
I started off with the CX430 and then I switched to the XFX TS 550 so we are just trying to save you the hassle of a getting a XFX TS 550 after buying a CX 500 since everyone starts overclocking their video cards particularly during winter.