I bought the N900 used but in new condition with Zagg screen protector already on but with couple of scratches and little bubbles that were not a big deal.
I order the TrueVue anti-glare screen protector from Amazon.com took three days for delivery, first thing i did was to take off the previous protector (zagg) and apply the new one.

All four edges were not sticking for some reason. i was not happy with this screen protector that i decided not to use one.

Had it like this for a week, i have maybe three small hairline scratches that are only visible if you point it directly to the light.

Screen looks awesome without screen protector and feels good too. Im sure i will get more scratches but i prefer the regular feel that the rubbery.