Been meaning to write this up for a little while now so here it is (assuming the box is all built with ATI card(s) installed):

1. Install Ubuntu (10.10)
2. Remove the drivers it will automatically install that will conflict:

sudo apt-get remove --purge fglrx*
sudo apt-get remove --purge xserver-xorg-video-ati xserver-xorg-video-radeon

3. Re-install some prerequisites (not sure if they are needed but it doesn't hurt - java is definitely needed for Diablo):

sudo apt-get install --reinstall libgl1-mesa-dri xserver-xorg-core
sudo dpkg-reconfigure xserver-xorg
sudo apt-get install sun-java6-jre

4. Install the proprietary ATI driver you can find here by:

chmod +x <file_you_just_downloaded.run>
sudo ./<file_you_just_downloaded.run>

When it asks you if you want to build a package for your distribution or just install the defaults, go with the defaults.

5. Open a terminal and enter:

sudo aticonfig --initial --adapter=all

This will create a working xorg.conf file. If this doesn't work you will have to re-boot first. In any event re-boot after you have created this file so that you will be running using the proprietary ATI Catalyst driver.

6. Download and install the OpenCL dev and runtime packages (i386 or AMD64).

7. Log out and then back in to initialize the OpenCL libraries. If you have more than one GPU you will have to issue:

export DISPLAY=:0

in order for all your GPUs to be seen by your mining software.

8. Download and untar Bitcoin. Look in bin/<your_arch>/ to find bitcoind. Start it. Use ./bitcoind getinfo to confirm you have the blockchain and some connections to the network. If it's your first time running it you will need to set an RPC user and password that your GPU miner will need to authorize with. To do this create a 2 line file at ~/.bitcoin/bitcoin.conf that contains rpcuser=<your_RPC_username> for the first line and rpcpassword=<your_RPC_password> for the second.

9. Download your mining software. I only have experience with Diablo. Start it up by running:

./Diablominer-Linux.sh -w128 -u <your_RPC_username> -p <your_RPC_password>

You can also throw an "f" value in there to control the interactivity of your desktop.

If you wish to try m0mchil's Python-based miner hit this thread and follow the instructions beginning at the line that says "Download PyOpenCL".

You should see your miner start showing you a hash value!

PROFIT ;-)

If you wish you may want to overclock your card. I pushed my clock speed to max and left the memory at stock.

Please let me know if this sequence doesn't work as this is all from memory. I'm happy to troubleshoot your setup, such as I am able, and revise these notes. I get about 343Mh/s (w/ Diablominer and -f1) from a 5870 using this.

edited with feedback from users of this guide