Everybody on here has very good suggestions. Bottom line it comes down to your choice and what you think will be good for your gaming and learning needs. If I was in your shoes which I was at one time.
I would get the best card that money could buy with your budget. The reason I say this is because everything is getting more advanced including games and other softwear, making the smaller cards obsolete.
The biggest card on here for your budget is the 6670. Here is another link to a HD 6670 it is in the 90's but with the rebate it comes out to 70 something. Good luck to you.http://www.microcenter.com/single_product_results.phtml?product_id=0363815