The maximum resolution you will be able to use is in this case limited by the monitor, 1280x1024@60. You will not be able to max out the resolution of the video card but whatever settings you currently use should work fine with the 4870. To be honest the 4870 is probably overkill for a 17" crt, but you should be able to run with very high graphics settings and if this makes you happy then who am I to argue?