Which version of photoshop should I buy?r?

Since you're a student you're tremendously lucky in that you can get 80% off the regular price of Photoshop CS5 Extended - whereas with Photoshop Elements, the price is only discounted 30%...

http://www.adobestudents.com/

So the net effect is that the full Photoshop is relatively a lot more affordable

Regardless, you should definitely avoid the older versions of Photoshop Elements because Adobe no longer sells them - and consequently there are a lot of fakes floating around there which are often unsafe and harm your computer

As for the differences between past versions of Photoshop Elements, version 9 is the best because it now includes some Content-Aware Fill features which will make your life a whole lot easier. For the rest, see

Compare Versions: What's the Difference between Photoshop Elements 9, 8, 7, 6?

http://prodesigntools.com/version-compare-differen...

Of course, you can also always just download a free trial of any of the latest versions of Photoshop direct from Adobe and try them out for yourself for 30 days

http://www.adobetrials.com/

Hope this helps!

If you're going to major in graphic design, you might as well get one of the full CS5 suites. Your academic discount is the best way to get Adobe products for cheap.

Otherwise, I'd stick with Elements 9. I've heard people have compatibility problems with 8, and the older versions are lacking in features.