I'm not arguing the content, but if you show most people these 4 stories, they may not be all that convinced.
The first story's evidence is just the statements from Rubin and Gore that it happened in the 80's, though no facts are presented to back this up. It mentions hearings that were going to be held on this issue. China denies that any spying ever happened.
The second story refers to the (yet unnamed) Wen Ho Lee (who wasn't even tried on spying charges
http://www.sfgate.com/cgi-bin/article.cgi?file=/chronicle/archive/2001/08/02/ED128240.DTL), and also references "Officials" believe that spying began in the 1980's but the first evidence is from 1995. While there is some time delay between the time you steal secrets and the time you put them to use, this doesn't really set a specific time line.
The third story rehashes the same Times story as the earlier stories, so it repeats the same information and doesn't really add anything new, other than that one official said the unnamed suspect failed a lie detector.
The 4th story is better, as refers to an actual investigation that took place, but only says that over the last 2 decades they "found that national security harm did occur". This doesn't say that it only happened in the 80's, just that it happened over the last 2 decades.
Since these articles seem to reference the NYT article so much, and the article seems to have been off the mark about quite a few things, you might do better to see if you can dig up the results of the Cox hearings on this. Any freeper worth his salt is sure to bring up the control of certain "dual use" (has both commercial and military applications) technologies that were transfered from the Defense Department to the Commerce department and then sold by Loral Space to China. You might want to research this a little as well just to be prepared.
I'm not trying to give you a hard time here, but personally I'm not a big fan of citing CNN as the basis for any of my arguments.
Good luck!