cable and interconnect advice?

Purist Audio Design Poseidon cables is my vote.  Warm, lush, sweet top end, highly detailed throughout, with tight/punchy controlled bass.  Very musical.

Don't listen to people or reviews TOO much.  Get your hands on a nicer cable, maybe from a seller that is willing to let you have an in-home demo period.  Play some music you are familiar with a couple of times with your current cables and setup, then play those selection(s) at the same volume, in the same listening session with the new cable you are trying and listen to the changes.  Listen for the soundstage size, transparency, detail, speed during fast successions of notes.  Listen to the separation of notes, say the low bass guitar and the kick/bass drum.  Listen to the percussiveness of everything really...one will sound soft and boring, the other will be punchy.  One will be more smeared, there will be more blare, more harshness, more fatigue, and the other won't.  One will sound more "real" to you.  
And...if you don't hear a difference, that particular cable isn't worth purchasing.  Those who state that you shouldn't spend anything on cables are flat wrong.  Sorry.  I wish it wasn't true, but it is.  Cables are part of the system's sound.

I second stringreen's comment, I've found power cords to make the largest difference, then, for me, it's a tie between the speaker, interconnect and cables.
Also I second ghosthouse's comment, don't listen to us, reviews, audioholic bloggers, get your hands on a few different cables and listen.  I would not say cables are subtle, but I agree that the speakers are first, and electronics second, but the cables are right there too.  Listen to a few cables with your ears...you'll find which one works the best for your system.