EXS 24 Logic Sampler Users Group

I have a dual G4 867 with 768 RAM. The amount of tracks and plugins you use seems about the same as me. Actually, I think I probably use a bit more. I do lots of effects while bussing also. I dont seem to have a problem...especially now that I use many instances of the EXS sampler. I also use Spectrasonics Stylus and occasionally a couple other instruments. I have gotten much better using few different instruments.
At any rate, I believe you will be fine, at least for your applications. If you follow a few tricks to help with your processing power you should be ok. For example, remember to set the number of voices on your instruments to no more than you need.
Also, I am running Logic 6 on OSX. Logic seems to use the processing power more efficiently. Im also wondering what you will be doing about software since you will be changing from PC to MAC.
My other suggestion is that you should probably scrap the 22" cinema display, save that money, but then put a little more money back into it by getting a dual Gig perhaps. If you are willing to pay for the cinema display, which you probably do not need....you would save money by not getting that, and getting more processing power.
Hope this helps.

Pete