6-week south america trip HELP Please!
 

Hi, I'm a student and I'll be studying abroad in Santiago, Chile from February-July 2009. I'm planning on arriving in Chile in the beginning of January to do a 6 week (maximum, but maybe shorter) trip traveling to several countries. I'm interested in visiting Argentina, Paraguay and Brazil. I've been to Peru, so I'm not worried about seeing the amazing sites there.
I am in the very beginning planning stages of this trip and I'm wondering about the feasibility of several things. The places I'd like to visit (very tentatively) are: in Argentina- Buenos Aires, maybe Cordoba and/or Mendoza, and Iguazu falls; in Uruguay: Colonia and some smallish beach town (any suggestions?); in Brazil-- Rio, Salvador

I'm on a budget, and although I realize this trip will cost a lot, I'd like to keep it as low-cost as possible. For that reason, do you think I can take buses to/between most places, or would a plane be necessary for the longer distances?
Also, I'm a female most likely traveling alone. I've done some solo travel before, but is there any place/mode of travel that I should be wary of?
I'd really appreciate suggestions of where to go, and how to get from place to place. I'm really open to changes since i'm really in the pre-planning stages. Thanks in advance for your help!
~Elena

You might want to also post on the Thorntree - Lonely Planet forum - lots of great budget advise there.

Thanks, I'll make a post to thorntree :)

ok, i realize this was a really broad question.
Let me be a little more specific. Is 6 weeks enough time to go from Valparaiso to Rio with several stops in Argentina and a couple in Paraguay along the way if I want to travel by bus?

Should I forget about going to Brazil since it's so far?

I'd appreciate feedback!
Also, I couldn't post on lonely planet because it wouldn't let me register properly :(

Any suggestions? PLEASE?! I know it's a big question, but I'd appreciate a response from anyone who has done a multi-country trip in this area.
Thanks!