Is it worth the improvement?

Hello,

I was considering buying a Sapphire Radeon HD 7750 1GB GDDR5. My current graphics card is a Sapphire Radeon HD 6570 1gb DDR3.
The problem is I have a old Intel Core Quad Q9300 2.50 ghz proccesor and I was wondering if the improvement in all of the new games will not really show up because of the proccesor bottlenecking. I will mention that I have 4gb of ram DDR3 1333mhz too.

Could I run some of the new games at 1920x1080? Or at least run games like Far Cry 3 on low or something?

Thanks in advance! and sorry for my english.