I'm going to weigh in here too.
It's best to start small, especially if you two are new to "digital music." Don't buy hardware synths, mixing boards, or even expensive sample libraries like VSL or EastWest. (By the way, EastWest's complete symphonic sample library is over $1000, while VSL charges that much just for the strings samples.)
If you already have (or are willing to buy) a decently powered Mac, you'd be surprised what you can do for super cheap. Here's what I recommend to start with: Logic Studio with a cheap MIDI controller (you can get them for under $100). Logic Studio has all the mixing tools you need built in, so you won't need any hardware unless you want to record multiple audio tracks simultaneously. It also has tons of samples, including orchestral, world, and 80's-style synths. They're not on the same level as the super-expensive ones, but they're pretty good, and it gives you a "complete" musical sandbox to play in. That plus the MIDI controller will run you 600 bucks.
The reason I think you should start with something like this is because you really won't know what you need until you've tried something out. If you decide later on that you want better-sounding string samples, no problem; just buy some. You still get to keep using everything else, so it's not like you've wasted money.
Good luck to both of you.