First off, I know I don't *need* a Mac Pro. I haven't really pushed my MBP to its limits yet -- I write mainly minimal techno and house pieces and I use my MBP for DJing too. But I just bought Native Instrument's Komplete 5 (which takes up a crazy amount of space), and an external OWC Mercury-on-the-Go hard drive, and I realized I'd probably be buying another hdd in the near future just to deal with all of the samples and project folders I have. I've also been looking to build a gaming PC ($800-900), so I thought I might kill two birds with one stone. I've kind of subconsciously stayed away from processor-intensive apps (I barely use Space Designer/Sculpture) and I haven't ever used NI's Massive (one hit and it took up a chunk of my CPU). Oh and the MBP seems to be pushing its limits driving this 30" ACD. So to those of you that have upgraded from a MBP to a Mac Pro, or downgraded from a Mac Pro/Powermac to a MBP -- was it worth it? Is there a big difference between the Quad and Octo models (in music programs)?