It really depends on what you are asking it to do. Presumably it will be a hybrid (both core and the media director, rather than 2 machines) this can increase the load, but if you are just doing basic media stuff, generally LMCE doesn't require high end specs. The pure MDs are a little lower in requirements. If anything, for a core you might want to throw in another 512MB, not so much because it is required unless you are intending to do heavier stuff, but because it is so cheap! A spec'd up core that you intend to use in production with a higher load (eg multiple video streams, or automation, and lots of media) then I would say 2GB is oodles most of the time.
By all means play with what you have - when you decide to buy hardware, though, research the options well as it makes the difference between a completely smooth, trivial install and getting yourself tied in knots (esp video).
