I agree with the other folks that you've barely provided any information. If it's a place for composing, arranging, don't buy ssl plugins and ozone. Invest in virtual instruments instead. As wild as the MacBook pro's are these days, a Mac pro is much better suited to a production environment, especially where heavy virtual instrument use is concerned. Huge amounts of ram, multiple hard drives, and beefy processors are a prerequisite. Depending how much virtual instruments you'd use look into ssd's and/or raid arrays. Some of the orchestral stuff (or even modern instruments) would eat 8gb of ram for breakfast.
Think about workflow, too - from good midi controllers, a setup that will be fast and easy to work with (patchbay? Headphone system? All the adapters, di's, cables... Guitar tuners, stands, what have you), down to the ergonomic layout - convenient desk with enough space to work, good chairs, and enough of them.... The little stuff gets overlooked way too easily IMO.
Anyway the most important thing I'd say is to spend the bare minimum possible to get the most minimal setup going, then use it for 6-12 months and slowly spend the rest on stuff you find you absolutely need.