$2000- step up integrated or seperates?

I currently own a 2 channel pretty low watt/channel Rotel amplifier. In the future I will probably scew my purchases towards home theatre to accommodate TV/DVD/and music. (This next purchase will likely be my last purchase in terms of amplifiers for many years).

What would be my best bet?

a) Step up to a multi-channel integrated amplifier that can one day accomodate 4 speakers+ subwoofer?

b) Get seperate Amp and Pre-amp that will accomplish the same as a.

Also what would you recommend in terms of models?