Email blast works in everything except prior to Explorer 8

Am sending out a email blast that I did. When almost anyone receives it (still testing it) all the links work. When people with lower than Explorer 8 get it - none of the links work. It works in AOL email, entourage, safari, firefox, opera and Explorer8

I CANNOT figure it out - I keep redoing links and looked on line for an answer and cannot find. This is the url that I am sending the email blast out from.

http://www.pdtest.com/mk_eblast/eblast.html

There must be something I need to put into the code so that the older versions will click the links.

The links are paragraph 1 & 2 and the click here spot on the bottom

Thanks
Barbara