You have a year in which to prep, motivate and educate. IMO, not many guide books or DVD's are as good as current ride reports. These offer timely info from folks out on the road NOW or recently returned. Most of the links below started in N. America and moved South into S. America. But all good info and inspiration. Take your time, read the ones that interest you. Leave the rest behind.

I agree with buying a bike once you arrive. Lots of travelers' bikes for sale, some great deals on some great bikes. You just have to figure out the paperwork. Shipping your AT will cost $$$A LOT.$$$ If you buy in Argentina on a Argentinian plated bike ... you can't leave the country with the bike!!!
If you buy from a foreign rider, you can, but you'll have to "fiddle" the paperwork at the border.

ADV Rider seems to collect many of the best S. America Ride Reports. There are a few duplicated here on HUBB but many more on ADV Rider which has 30 times the traffic of HUBB (and 30 times the BS).

Here are a few of my favorite travel reports. There are dozens here and there to choose from. You will learn a lot from all of them:

South America and back on a 250 Super Sherpa Minimalist Adventure - ADVrider
JDowns (one of the best reports)

RTW on a thumper...KTM - LC4 Round the World ADVenturization - ADVrider
RTW Paul (A+++ ... good border info for Cent. America)

Jammin thru the Global South - ADVrider
Jammin Jay (Starts in USA, then Latin America and beyond)

No Jobs, No Responsibilities, No Better Time then Now - ADVrider
Big Al Smith (crash fest and recovery)

http://www.advrider.com/forums/showt...50+Baja&page=3
Jedi Master S. America (best photos going!)

South for a while… maybe longer - ADVrider
Air Borne Andy (lots of good info)