I'm sure it will look better on a high-end PC, but probably not "next-gen". I built my PC myself over Christmas for about $700 (ordered all parts from Newegg) and I can run all the newest games at highest settings. If I were to order the PC already assembled from Dell or Alienware or something, it would have cost over $1500. Considering the PS3 was $600 at launch, I think getting a high-end PC is a better investment.
You can't really compare console pricing to the price of a pre-built PC. Consoles are regularly sold at a loss, so that $600 was for hardware that cost Sony significantly more than $600 to put into their machine.