Well thats a much much better card than you have and its on special this week so is kinda a bargain!
You should be able to make it look better with that card!
Remember to get rid of old drivers using a program like 'Driver Cleaner3' make sure its clean of old bits of drivers!
Then install the new ones and you should be good to go. Think the latest ATI cats are 4.10. You can get them from
www.ati.com Choose driverm then your OS then your card type which is Radeon.