Random thought of the day:
I feel like you're the kind of person who would like a Modular PSU. Makes cable management (and basically everything else for that matter) a lot easier and neater.
Recommend the OCZ ModXStream Pro; 50w less powerful, though... you give it up for the sexy-factor...
Sorry about that. You'll have to excuse my obsession with Modular PSUs...
Anyway, just to back up the crowd even more, yeah, it's really that easy. Not much else to be said.
The really tricky part comes in cable management, which may just be on the edge of nonexistent in an HP system. I'm sure you can handle it though. Words of reinforcement, those are.