I used to cut/edit audio and rip vinyl on a rescued Dimension 4400, so I'd argue the i5 isn't required if that's all your friend is doing. I'm not saying he shouldn't get an i5 if he wants power, but he's factoring in a huge chunk of his budget for something that might be overkill. -- Support Bacteria -- It's the Only Culture Some People Have
I'd actually start by asking what his current "all out" 1366 based system can't/doesn't do that a new build will. Does he just have the upgrade/new build itch, or is it something else? There is no wrong answer, just curious. :P
To Fizzy: "Sound Card? I guess we stick with on-board?? Realtek ALC898" If this guy does "heavy audio recording work" he should have something like a RME Hammerfall DSP 9632 card for audio processing or something similar for audio input/output.
I built a i5-2600K/P67 based machine with a SeaSonic S12II 620, 8GB (4x2) G.Skill X Ripjaws and GTX 560 about a year ago for a buddy with a "serious" home studio (with the aforementioned RME card into a Yamaha MG32/14FX mixer console) about a year ago. So something similar with current parts should do just fine. It also handles video editing just fine too (for editing his bands shows/gigs).