Newegg.com is where I get most of my computer parts and they are good to deal with.
I haven't A/B'd the wireless vs. wired sound, but it sounds like Ted has done so.
I don't believe the length or quality of ethernet cable makes any difference in this case, due to the nature and method of data transfer. It is very different than a 'digital' cable where data, clock, etc. are all combined in a SPDIF signal that is essentially deconstructed and re-clocked on the other end.
Just my $0.02.
Thanks,
Dan W.