UPS

I am about to buy an APC UPS, can't decide on either a CS 500 or RS 800.
Chris Brown wrote on :

Hi All,

I am about to buy an APC UPS, can't decide on either a CS 500 or RS 800. iMac 24, second 20" monitor, external 500GB HD are all I am concerned about at the mo. Don't really need extended work time, just safe shutdown execution time; but multiple recovery in the course of the day is occasionally an issue.

Anyone have experience with these?

regards

Chris