Getting a GPU Bitcoin miner for Linux 64bit

Here is a list of the currently available miners. Most of them support Linux:

GPU

• DiabloMiner - Support: Windows, Linux, OSX Features: Long
  Polling, BFI_INT
• poclbm - Support: Windows, Linux. Features: Long Polling, BFI_INT
• hashkill - Support: Linux .Features: Long Polling, BFI_INT, Auto Reconnect
• Phoenix - Support: Windows, Linux. Features: Long Polling, BFI_INT, Auto Reconnect

CPU

• Jgarzik - Support: Windows, Linux
• Ufasoft - Support: Windows, Linux. Features: Long Polling, Failover

FPGA

• FPGAminer - Support: Windows

Front Ends :

• GUIMiner - Support: Windows, Linux. Features : poclbm, ufasoft, phoenix (phakt support)
• AOCLBF (Formerly Phoenix Rising) - Support: Windows. Features: Phoenix (phakt support)
• Diablo and RPC for Mac - Support: OSX 10.6+ Features: CLI Frontend Setup
• BitMiner - http://forum.bitcoin.org/index.php?topic=12135.0 Support: Windows Features: poclbm, (Planned) Temp readings / usage

Taken from here. Personally, I am using the GUI minner (which has the poclbm backend). It was easy to setup and it's running fine at Ubuntu 10.10 64 bit with an ATI card.

In my experience, Linux is far better supported by the Bitcoin community than Windows is. The same goes for ATI vs. Nvidia; ATI cards are far better at doing the calculations required for mining bitcoins, so all the serious miners use them. 32 vs. 64 bit should also be a non-issue; just pick the 64-bit version of the AMD Stream SDK instead of the 32-bit version.

Here's a guide for setting up the Phoenix and poclbm miners on Ubuntu 11.04. Setup should be roughly similar on other distributions.