I use Adobe PhotoShop CS1 and Corel Painter IX. If you like working with more traditional mediums such as acrylic and oil paints, get Painter. PhotoShop is a good all around paint program but Painter has better brushes and is more like traditional art. I was able to get Painter for $100 at my school. You might be able to get a similar discount (see bottom). I was also able to get the whole Adobe Creative Suite (photoshop, illustratior, indesign, and... something else) for like $200 at my university. Regular retail price is $1,000 for that suite so there are deep discounts for students if you know where to look.

The tablet you'll want to look for is a Wacom tablet. There are I believe two or three different models. The cheapest one I think is called "Graphire" and is about $90 (this is the one I have and it works fine for me). But if you want a greater range of pressure sensitivity and accuracy, you might want to get the next model up, the "Intuis" or something like that. Each model also comes in different sizes. The bigger the size, the more expensive it is. I'd say, start off with the small cheap one.

If you are a student, you can purchase your software and tablet from one of these two sites and get a big discount. I've used creationengine a few times in the past but i don't think i've ever used the academic superstore. These days I just get my software right on campus. I love SJSU :D Anyway, here are the sites:
http://www.creationengine.com
http://www.academicsuperstore.com

Hope that helps.