How do I perform Apple Hardware test?

I have the white MacBook, came with Snow Leopard and now running 10.7.5

How do I run the Apple Hardware test?

I tried following the instructions given in help but AHT screen never came up. Any way of doing this other than going to Apple service center?

jav6454 said:

The recovery disk should contain the instructions on how to do it. Otherwise, just insert the disk before startup and press+hold T.

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Recovery disk is the Snow Leopard disk?

Weaselboy said:

The grey, Apple installer disk that came with the machine is what you want.

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Okay, got it. Thanks!