I read this thread regarding replacing the antenna. Before buying the antenna, figured to take the thing apart and see what I was getting myself in for.
There is a youtube video regarding how to take it apart. Pretty easy.
Found the antenna per the photos posted in this thread.
One point to make, that was not 100% clear to me, but is now that I took mine apart - the antenna is NOT soldered to the board. It is attached with an U.FL connector - it just pops off.
So - this will be very very easy to replace the antenna. Simply buy new one, pull old one out, snap new one into place.
If the new antenna does not have a wire, you may would have to use the old wire, which would require a solder to the antenna, but that is outside the tablet, so fairly safe.
And, last but not least - in snapping off the U.FL connector on my tab, and reconnecting it during my "dry run", I fixed my connection issues! So apparently the connection had come loose in shipping or what have you. I now have the same signal on wifi analyser as my htc inspire, and the other a500 I bought for my daughter. (it was nice having two a500 side by side, so I knew one was fine, one was bad - mine of course).
I plan on seeing how this works out, and may still replace the antenna.