it made sense to do this years ago when computers were very expensive, but now they are dirt cheap why would you want to go through the hassle of this?
you want to have it service 3 separate users from what I've read, so rather than buying one high powered computer for $2000 (just picking a number for a sake of the example) that can handle all three at once, instead get it like this:
user one does a bit of gaming: $1k machine built up from newegg
user two watches movies, heavy web browsing, uses office apps: $700 sourced from newegg
user three just checks her emails and her favorite news websites: $300 ex-lease computer from your preferred friendly local IT shop