I made my own screen protector using 3M Transparency film and the template at this link:
http://www.jaytmedia.com/ppc/
The screen protector works great! So much better than the WriteRight crap. And, so much cheaper than the Write Shields.
I simply printed the template on a transparency, cut it out carefully, and slid it into place. Of course I made sure my screen was spotless before applying. I see no difference in screen sensitivity, the protector doesn't slide around, and i don't have the bubbles you get with the adhesive protectors.
I encourage you to try it before you shell out the big bucks for the commercial protectors.
Can you imagine the profit margin on a package of 3 Write Shields for $30 bucks? Wish I had thought of it first.