He was from Oklahoma...
You need a stronger heart.
First hate (and really only hate) will always be Philadelphia. No exceptions.
The key point in your post is, "I might have been a kid during the Aikman era". Which means you most likely remember the Superbowl championship in January of 1991, which helps.
Had you been a kid during the 1970's Roger Staubach era, when the Giants stunk. You might have a stronger sense of hatred towards the Dallas Cowboys.
For the record: The photo doesn't kill me. I was going for a little humor here, when I saw the photo on the internet last night. Mickey lived in Texas during his career, so I'm not shocked to see him wearing a Cowboys shirt. I probably would've posted an identical thread if I saw a photo of Eli wearing a Boston Red Sux shirt.