The purpose of that command was to identify the malfunctioning device. In that respect, it did it's job and helped quite a bit. ATI in general provides good drivers for Linux and works hard to ensure that their devices will work properly on a Linux-based OS. You can rest assure that the device will work one way or another. Linux Mint 8 Helena is based, and on large part is, Ubuntu Karmic Koala 9.10. A possible bug has been documented in Ubuntu, so it is very plausible for mint to have it as well.
jremy, could I ask you to attempt to use proper grammar, spelling and punctuation? Also, CLI output should be put into [CODE] tags, by highlighting the output and pressing the [#] button in the advanced editor. It also helps to make your post as descriptive as possible with as much information as you can gather, as this can make the process of diagnosing and fixing the issue go much quicker, and with a higher rate of solving it all together. Also, always try to make the thread title as descriptive as possible. Remember, we already know you are new to Linux from where you chose to place your post. These are a few things that can help improve the readability of your post and hopefully attract more replies. One last subject I would to address you on is 'homework.' It will always attract more replies if you choose to find a solution yourself and attempt it, then post your failures alongside your problem. This shows you care. Anyways, this is just some LQ etiquette that can make a major difference in the quality of your experiences here on this great forum. Now, to address the problem.
I researched the topic, and located a few solutions to the problem. However, we should first ensure it doesn't work in your current setup by using jstephens84's suggestion.
Please, open a Terminal (a command line interface), and type in 'alsamixer', and press enter. You should see a few bars come up. This is where you will want to turn up your sound. Turn all items up to 100, and then run any desired audio test to identify if its just a Graphical User Interface problem (GUI). If it is not, then continue with the proposed solution below.
1. Type into a Terminal: "kill slmodemd". If the command returns an error, that is OK, since all that means is you don't have that anyway.
2. Use alsamixer or the GUI, configure your sound and test it. If it remains silent, continue below.
3. Open a Terminal and type in "sudo apt-get linux-backports-modules-alsa-karmic-generic", and install it.
4. Restart your PC.
5. Verify you have followed the above instructions correctly, use alsamixer, and enjoy your sound.
I am glad that you are happy with Linux Mint, and I hope the solution fixed it. If it did, please read my signature and post back. Have fun!