There is no such thing as the ultimate stress test... if there no signs of instability during daily use, eg corrupt extraction of RAR files, errors while copying, abnormal program terminations you are fine....

some prefer LInX ( linpack stress tool ) but for SB you need to install SP1 for Win7 for proper testing. Some prefer Prime95 small and blend, some do hyperpi32 ( all cores selected ) FYI I can pass all of them yet still crash during online gaming lol...