Shouldn't matter - signal from N900 TV-out never exceed PAL, so it's rather matter of "does it convert properly to PAL and send signal at all". BTW, PAL get little higher number of lines (let's critically oversimplify it to "resolution"), so on already crappy low-res TV-out, it's best to use PAL when possible. Also, remember about TV-out control status menu widget, which allow You to scale output, change aspect ratio etc.

/Estel