I found via JuliaL49’s here (in German) the report of the US Congress’ Democrates – sources: BBC News and Tagesschau, also CNN – which states that the war in Iraq and Afghanistan will cost the USA from 2002 to 2008 thanks to “hidden costs” 1.6 trillion dollars – $20,900 per US family (or $5,300 per person), possibly increasing to $46,400 by 2017 (that’s $3.5 trillion total).
Numbers that make you go dizzy… it’s just not clear how fast they could withdraw in a sensible manner (assuming they want), and I agree with Julia that a fast withdrawal doesn’t seem to be an optimal solution.