Looking for a quiet graphics card upgrade

Hi, I currently have a 512Mb Radeon HD 2900 Pro, which is still satisfying my gaming needs. However, when the fans kick in it is extremely loud (I think it's ~55-60dB). I'm not looking to break the bank with an upgrade because I'll probably build a new system for myself some time next year, but I would like to get a quieter card with a moderate performance boost in the meantime.

1Gb Radeon 4850s and 4870s look pretty attractive, but I can't find noise stats for them. I would also be open to NVIDIA cards (I buy Radeons only out of habit). Any input the community could provide would be appreciated, even if it's just links to resources where I can find information about the noise cards put out.

Thanks!