If you've got a brand new PC, with very little installed on it, possibly 'yes'. Otherwise, almost certainly 'no'. The more software you install, the greater the chance of unnecessary programs being added to your start-up group.
I've just taken a look at my own list and there are quite a few things in there I don't really need at startup (e.g. WinAmp). Take a look yourself and see what you've got. (Start > Run > type 'msconfig' > OK > Startup tab. At least that's what it is in Windows Millennium. XP probably makes it far harder to find!).
Chris