I know nobody asked.
But IMO if you're looking for a very good OS X Tower for under $1000,
these or even a Dual 450 would be a great choice.
In OS X it probably takes a single 933 to beat them.
They're showing up at good prices.
Used G4/500 dual, 256/40/DVD-RAM, Zip 100, $895
http://new.lowendmac.com/ppc/deals.html