mostly people tell you what kind of computers to avoid rather than which ones are good.
I know, we're so unhelpful aren't we? :P

I hear ya on using the computer a lot. It can make it difficult with warranty on a custom-built computer if something does go haywire, however I guess it really depends on where you get it built. If you make it clear that you plan on using the crap out of the computer and would like some sort of assistance if something does happen to it, I'm sure they'll set up a good warranty for you.