Best hardware testing ?

[RimBlock]

Hi,

What do people feel is the best way to test hardware before purchasing if they had the option.

Ideally testing should be no longer than 4 hours.

Motherboards:
Processors:
Memory:
Hard drives:
Optical drives:
Video Cards:
Controller Cards:

I am aware of memtest for the ram and maybe the hdd manufacturers own utilities fro hard drives but not how to best test other components.

Suggestions ?

Thanks
RB