Advice for my Jan-March trip to South America!

Hello everyone- I have purchased a ticket to Lima on Jan 7, 2010 and a ticket home from Buenos Aires on March 4, 2010. How I spend the time in between is to be determined. My plan is to hit Peru, Bolivia, Chile, and Argentina, in that order. I am looking for any and all advice you all may have for me. Things you wish you had known, that sort of thing. Also, I have $2300 set aside for the two month period, will this suffice? Thanks for your help!