Power Conditioners vs. Power Cables

I couldn't find anyone discussing this topic... if I'm mistaken please advise.

Does one negate the need for the other? In short, I want to know if my recent acquisition of a Monster HTS-5100, which noticeably improved the sound of my system, precludes the need for me to consider upgrading my power cables, as well, in hopes that it could further enhance the sound.
I’ve heard that there was no point to it with a power conditioner... that it was all I needed. Does anyone feel differently? I'm not sure what the general consensus tends to be on this issue.
I was of the belief that the power conditioner served to clean up the power from the city, but that the power cable would improve the transfer of the now 'clean' electricity from the conditioner to the components. Am I wrong and wasting my money investing in upgraded PC's? Or, is there, definitely more room for improvement to be had?

Thanks in advance!!