I've just tried IdleX on the Pi. Its an extension for Idle which gives lots of extra facilities including three I really wanted:
- Line numbers
- Multiple tabs
- execution of lines or sections of code in context
and it seems just as quick as Idle, certainly much quicker than Geany which is nice but very laggy when typing. Seems OK on Windows7 as well
Its easy to install, get it here - http://idlex.sourceforge.net/