Here's a benchmark pcWorld did:
http://www.pcworld.com/news/article/0,aid,112749,pg,8,00.asp
This is the last page of it where they have the nice chart, so if you want to read it all just check the other pages.

Here's a link to the "Aurora" line of alienware machines:
http://www.alienware.com/system_pages/aurora_ddr.aspx
Note that these are *single* athlon 64 systems, and they outperform the dual 2.2 Ghz g5 on half of the benchmarks. Also note that the specs on these Aurora's are better than the ones used for the benchmarks, and the cheapest one here is only $1.5k...

I can't find a link to the polywell machine listed, but this is their site if you want to check it out:
http://www.polywell.com

[black]-"The further we go and older we grow, the more we know, the less we show."[/black]