The board is supplied "bare-metal" - no code, no OS. You will not be able to run Linux on an AT91SAM7X-EK - it has insufficient memory resources and rins at 30MHz tops (and has no MMU).
You need a hardware JTAG or DBGU interface device and a tool-chain that will work with it.
You should probably also be looking at the datasheet for the board itself. From the Getting Started section of that:
The AT91SAM7X-EK evaluation board is delivered with a DVD-ROM containing all necessary information and step-by-step procedures for working with the most common development tool chains. Please refer to this DVD-ROM, or to the AT91 web site, http://www.atmel.com/products/AT91/, for the most up-to-date information on getting started with the evaluation kit.
So start there.