6+ year old pc/os. should i upgrade?

looking for some general advise here. just got into pc audio. starting out with a new 1T HD in a 6 year old system ($110). Vista os, intel p4 1.8ghz with 2gb ram. decent sound and video card for it's day...6 years ago. the thing does everything i need. would not upgrade for a couple of years if audio had not gotten into the mix. have priced out some decent box's for about $900-$1000. (windows 7 pro 64, intel i7, 8gb ram, 1g-good graphics,1t++ hd drives ect..) . question is, does this stuff...the guts/os of a computer, have any effect on the sound quality in a wireless pc based system?. if it does, i'd be willing to move the update up. if not...would rather leave everything alone and spend the grand elswhere =).

using a psa perfect wave dac/bridge on a wireless (n) network.

cheers