OS: OSX 10.5.8 / XP (whatever is latest, I suppose)
TOOLS: Sketchup Pro 7, Photoshop CS3, 3DS Max 7 (or somewhere abouts that), Acid 6
HARDWARE: Macbook 2ghz / 2gb ram / Nvidia Geforce 9400M, PC AMD 3ghz / 4gb ram / ATI Radeon 5850HD
I can’t imagine the instability of modeling having anything to do with Unity. It’s more than likely all on Max 2010. I mainly do assets on my PC, because that’s where my tools are, then I do my work on the Mac. Every once in a while, I use my PC for work, but that’s just come up recently, since I can have it on multiple PC’s and my Mac (thank you Unity Indie!).
Power Mac G5 running OS X 10.4, 2.5GHz, Radeon X800, Unity, Blender, Photoshop, etc. No problems, although the machine is over 5 years old now (will be getting a Mac Pro next time they update them probably).