Good question.
Depends *a lot* on the curriculum.
If students are just being introduced to the idea of an REPL (read evaluate print loop) then
showing off more than one IDE at the outset might prove enlightening.
Show & Tell: Python with vim in Linux shell.
Show & Tell: Python with IDLE with Akbar font (one of my faves)
Show & Tell: Python with PyDev module (still being improved) in Eclipse.
The last one is what I end up using with students these days, but I've mostly used IDLE in other classrooms.
Kirby