I argee with billnchristy and emorphien, use bookshelves as mains to start off with; thay will make great surrounds latter on.
as far as 'which can be skiped for now', I think you can live without surrounds, although some movies are not the same without them (M Night Shyamalan's moives come to mind), there is no moive that won't bennifit from a good center channel.
yes, you can get the effect of a center channel with a stereo pair, but that only works if you happen to be sitting in the 'sweet spot', which is fine if it's only one (maby two) people, but if it's more than that, a center may be nice.
(edit: topspin posted as I was typing, I must type faster next time)