4850 is awesome for the money....really really cant speak highly enough of it. I picked my overclocked powercolor off eBay for £90 (£133). Thats about $20 more than a 9600GT, and another $20 for a mail in rebate from Newegg.
Not only will you run the games listed, you will run them well.
If you cant afford the extra $40 then stick with the 9600GT, it will give you some fun.