SD, my friend. Please don't worry, I have both systems, and the screens are identical on both units. If you pick up a pack of DS Lite protectors and use them on your DS, and
don't tell anybody, nobody will ever know.
For the record, I have a set of Pelican (I think) shields on my DS (also blue, purty, ain't it?). The shields are actually virgins. The prophylactic has been in place since I took it out of the box--never touched it. With the stylus, that is. I did clean it with the included microfiber cloth before sealing it up.
On yet another note, I am a big Tetris fan, we should swap friend codes. I'd look for you each time I was online. Do you have one of the Nintendo
USB WAPs? Way cool, and soooper easy to work with? I have one (natch), and I usually carry it with me. If interested, pm me.