To find out if it's specced for 1.33 GHz, check the engraving on the top of the CPU core. About the second line, it should list the CPU stepping, a 4-character word beginning and ending with the letter "A". Currently, the official stepping for the 1.33 GHz Athlon is "AXIA"; anything else, and your CPU is O/C'd.
Of course, if it runs stable at 1.33 GHz, this might not be such a bad thing...I mean, it's not every day you get more than you pay for... :wink:
<A HREF="http://kelledin.tripod.com/scovsms.jpg" target="_new">http://kelledin.tripod.com/scovsms.jpg</A>