No, I have windows 7, don't think it's a windows issue.

But! I FINALLY got in.
Here's what I did. I beat my face against the keyboard until I decided to take out all my rage on IE.
I put the security at minimum (Since I use firefox anyway) Cleared, my cache, cookies, basically ANYTHING I could clear. After that was done, I turned my firewall off (I use Vipre) and started up XIV

Behold! The play button was there!
After starting the game I turned my firewall back on, and got a notice that my IP had been changed.

So, could be a firewall issue, could be a conflicting IP issue, I'm no engineer.
Either way it's worth a check.
Good luck!