Chain line precision
 

I'm building up my new frame, and this is my first time building from scratch. I'm using a Phil BB the cups of which allow for quite a bit of freedom with the positioning of the cartridge in the shell. My question is about chainline: how precise should it be, and how do I check? I've got it set up; it looks straight, feels smooth; it is a bit noisy --but perhaps that's due to the new parts?
Need more details? I'm using a 1/8" drivetrain: Surly fixed/fixed hub, EAI cog, Izumi chain, TA track crank.

http://www.sheldonbrown.com/gloss_ca-m.html. Scroll down to chainline. A wealth of information!

Thanks, I just remebered to look there.

The better the chainline the quieter the bike in my experience.