Hey, I'm in a pickle about which Mac to buy. I really want the expandability of the Mac Pro. How much does a 2008 basic quad core Mac Pro cost? With as little ram, hd etc in? I'm either going for that or the high-end iMac i5.
You can get a dual 3.0 (8-core) for $1799 with a warranty and I'm sure hunting on eBay you could get an even better price. But then you have to buy a monitor, keyboard and mouse (airport card too if you want wireless but it is a desktop so run the ethernet and be done). The machine I posted will last you a good long time and you can expand but know that the cards that work on this machine may not (probably won't) work in your next machine.
If you already have monitor, keyboard and a mouse, then get a MacPro. You can always replace the CPU(s) with faster variants (from the ones that Apple put in there), also you can replace the graphics card and hard drives.
Well an i5 iMac has the same number of threads as an 8-core Mac Pro. But remember, virtual cores aren't as fast as physical cores. Photoshop won't be able to use all the cores. I think there is a new option in Premiere and AE CS5 to use all cores. As for Final Cut, that won't use all cores, but compressor will.
If you want the expandability, got for the Mac Pro. But you may want to wait since 09 prices will be going down.
The other thing to consider is that some of those apps need a lot of RAM. With a dual processor Mac Pro, you can have twice the amount of RAM. Also you should know that the i5 iMac, 2009 MP, and 2010 MP CPUs have an on board memory die which will make your RAM seem much faster. A 2008 MP CPU does not have this.