Am wanting to build a 2nd PC (and maybe more) with plans to upgrade from V6 Infinite to V8 Complete and am wondering what considerations to take into account.  I'm thinking of going with AMD Phenom II 6 core with 8GB RAM to start with, and Win7 64.  Currently I'm just rendering stills, not animations.  I would use Vue as my primary 3D app, though I have Bryce 7 Pro, and Carrara 6.2 as well.  And of course Daz Studio which I definitely use on occasion.  My goals are to increase system stability (slightly higher priority), and increase render speed - especially in scene development and to a lessor extent in rendering the final image.  Questions I have:

With V8 Complete I would get 5 nodes.  Is it better to build 1 render monster (high specs in CPU and RAM) or does having a little brother PC (or 3) used as cows really help?

When using Win7 (haven't had any experience with it yet), is home version perfectly fine to use?  Are there any benefits in system stability, render speed etc. that would be worth spending the extra bucks on a better version?  Is there any need or benefit to having all systems using the same OS?  My current one and only PC is running Vista 32 Home (gag me - not very efficient, compatible, or stable in my experience e.g. V6I crashes quite often).

Currently I have a dual monitor setup.  Is it easy to switch my I/O (monitors and keyboard & mouse from one PC to another?  Would I use a KVM switch which supports up to 4 PC's?  I would think that would be the way to do that.  I would save money and space by not buying extra monitors.

Any useful feedback would be much appreciated.  Thanks.