Hi Madhavi,
The requirements for TestExecute itself can be found at
http://www.automatedqa.com/products/testexecute/system-requirements/.
But you should consider your tested application and correct hardware requirements accordingly to make it possible for the tested application to run and function as expected and for TestExecute to load and process debug info.
The above greatly depends on the tested application. For example, it was near to impossible to use TestComplete (and its Object Browser) for one .Net application that was built with the use of several other .net-based technologies (like Application Blocks) on the Win7 machines that had less than 4 GB of RAM.