IMHO, the screenguardz suck. I've had a LOT better luck with something like what Javo Edge
sells. It actually uses a weak adhiesive on one side, and you REALLY gotta be somewhere dust free when applied, but they last a long time and make a serious improvement for glare.
The first ones we got for our 7100t's were actually a little too wide. You had to get that sucker on their perfectly or you'd see a lot of bubbles on the side. The last batch we got seemed to fit better, but don't be afraid to cut them down if nessisary. They can be lifted off and reseated, but I always ended up getting crap underneath and usually ended up having to start over with a new one. BUT... once you get one on good, all the effort pays off.