Recommendation for a new Mac Editing System 2012

Greetings,

I haven?t used FCP and a Mac for some time and I'm in need of advice. I'm going to be editing short films, web videos and documentaries which will be shot with a Canon T3i and uploaded to YouTube, Vimeo and Facebook. Some videos will be produced using green screen. I would eventually like to edit a feature with this system.

With the iMacs and Mac Towers currently on the market, could someone please suggest some configuration options for a new MAC edit system which uses FCP X for a reasonable budget? I prefer a desktop instead of a Mac Book Pro.

In addition to the computer, what other components or accessories would you recommend for this system ? audio mixer, external hard drives, second computer monitor, a TV monitor, etc.?

I appreciate any feedback.

Thanks!

Howie