And just for everyone else - out of all of the hints in the link in my last posting I believe changing the MTU value to something other than 'automatic' and less than 1500 seemed to fix the problem. Since I have switched the MTU parameters to "Manual" and 1472 for the MTU size I have nothing but successful uploads from the Eye-Fi card. I would suggest trying this trick first. Make sure you reboot the router after the change.
Next time I think I'll look at a D-link router or something other than Linksys for my home network for a couple reasons. One - the issue of "Dropping/Intermittent wireless connectivity", and two - the router although is gigabit it does not
handle jumbo frames which is needed to realize the full speed of a gigabit network especially if you are transferring large files.
I sincerely apologize for thinking that the issue was the Eye-Fi card, I should have known that Cisco would have been the culprit (we have other Cisco equipment at work and have run into a few bugs with the equipment there).