It will depend on what games your running, and the resolution you game at. In general, the HD4830 will not "bottleneck" your cpu, but it will bog down in high resolutions. What resolution is your monitor? If you have a 1680 x 1050 monitor (or lower) you should be fine.
I have an HD4830, and have been able to play most games (not always the latest and greatest) at 1920 x 1200, without AA. I have it overclocked to HD4850 speeds, which the card handled without issues. it's a great card for less than $100.