The Rhino+Grasshopper combo is probably going to be easier to get your hands on and learn on your own than, say, CATIA and with a little trial and error you can make pretty decent headway. There is also a wonderful support network out there for Grasshopper so you should be able to get the hang of it.
However, I think the most important issue with parametrics isn't really the software you're using but the way you're thinking about and approaching the problems. If you haven't yet read them, you should get your hands on some of Kolarevic's books, especially Architecture in the Digital Age. This way you aren't bound to just a program but can see applicable solutions across platforms.

You can get your hands on Digital Project, it is essentially CATIA but next generation. The educational license is $150 for students. If you are savvy with software, it shouldn't be too terribly difficult to learn. I became pretty good with it after 4 weeks, but I also had a project to work on. Otherwise, Rhino+grasshopper is easy enough to pick up. I second what Horn.MP said. Whatever you do, don't get lost in what the software can do, rather concentrate on what you can do with the software. Best of lcuk!

Horn.MP
Yup... the book about the way of thinkg is a good stuff that I'll try to get as soon as possibe. I think there's even more issue's - just need time to find out.

lost in stress
thanks a lot, but I think right now I need to focus on rhino+grasshoper due to a small amount of time, but I clearly understand that it's all is not only about the software, which is just a tool for your ideas.

Am I the only person left that still uses Rhinoscript?

Right now there seems to be plenty out there to read on the topic. Personally I'd recommend reading some Gordon Pask, Wolfram's New Kind of Science, and Stiny's Shape: Taking about Seeing and Doing. Basically focus on the principals behind the thought process rather than the process itself.

I have a friend at the AA, and he told me his introduction to parametric/algorithmic design was using processing (www.processing.org). It's open source and lots of tutorials online.

With that said, I would contact the school. Another friend of mine did the summer school last year, and from her explanation of the courses, it was anything but traditional "Architecture". It was more about social engagement/activism in different urban contexts. Their final project ended up being a book, but was almost some strange suit-like clothing that transformed in a way I can not remember. Anyhow, my point is: "Parametric Prototypes" might not mean what you think it means, so give them a call!

Pixelwhore-

I've tried to get into Rhinoscript and scripting in general for a while. It's just been difficult to find the time to sit down and really understand the syntax. I think I have a good idea of the theory behind it but I struggle a bit in the execution. Do you think the books you mentioned could help with that; do you have any others you would suggest?

The Rhinoscripting 101 PDF will teach you all you need to know about the VB scripting syntax. Like anything else I feel its extremely beneficial to have a project to work on rather than sitting down and learning it 'cold turkey'.

From my very limited experience with Processing/Java, VB.net, and Python it seems that VB script is a fairly forgiving language that doesn't expect too much from the user. I'm sure there are more experienced people floating on the board that can add to this. That being said, I'll be the first to admit that with the introduction of data trees and the VB.net scripting components Grasshopper is right up there with Rhinoscript as far as capabilities. For whatever reason I'm just more comfortable working with RS and am more productive with it so I haven't really forced myself to really get too into GH/VB.net.

We've been using SolidWorks for our parametric modeling studio. It's basically CATIA-lite; it's been pretty easy to learn. Of course, I've never used any other software for parametric modeling so I can't really compare. I think the student version is around $150 or so.