Firstly vista comes with windows mail, not outlook express. i see no reason why outlook won't work fine without it as its completely different software. As for IE, well there are bound to be some really badly coded apps out there that demand IE, but its unlikely it will cause a problem, also you won't be able to use the IE tab extension to Firefox if you come across a old, fussy and crap website requiring IE to work, but that's very unlikely, i would consider keeping it if this computer is used in a work or academic environment, they seam to cling onto strange IE related things, we had to do work using a macroware demo written by a rather past it lecturer for IE only, although most people now make sure they work on Firefox.