How come the buzz rolls for snares and tenors looks like every other regular note.  I'm scared to add an articulation due to the fact that it might change the playback.

Sibelius 3.1.3

In Sibelius I use the lyrics tool (Ctrl or Command + L) and type a ";z"; then drag it up to the stem.  It doesn't affect the playback in any way and is purely for the printed score.  There's probably a better way, but that's what I've always done.

Other than a ";Z";, buzz rolls usually do look like any other note. In Sibelius 3, I've typically just added a ";Z"; by entering it as ";Technique"; text.

Sibelius 4 has an official buzz roll Z that will attach to the stem, however it will affect playback. One way to use that Z (since it looks better than a text Z) is to enter it as a Symbol. Symbols in Sibelius will not affect playback. I believe Sibelius 4 will be shipping in a few weeks.

fyi, I just got my Sibelius 4 upgrade a couple of days ago - I ordered it back on the 12th (when you first mentioned it here in the forums :)

Glad to hear you've already received your upgrade Cory! Sounds like Sibelius is getting them out faster than I would have expected.