@adamodo,
For 100,000 polys, you are safe with even a GT 520. (Had one, could push up to 900 000 polys at 60 fps without the textures). The 750 ti shoud let you push around 1.5-2 mil verticies in Maya viewport 2.0.
As for ZBrush - yes it is true. ZBrush works in 2.5D so you can have rediculous ammount of polys without system slowdown. ZBrush uses mainly System Ram to store the geometry and preview, instead of using mainly vRAM like Maya. I use ZBrush only in my spare time, but I managed to get 20 mils without slowdowns on the machine you see in my signature.
VRay 3.0 is coming for Maya soon and it has some pretty nice features. One of them is that it has been rebuild from the ground up, specifically using Intel AVX optimization. The presentation from Chaos Group I attended did show around 30% and sometimes up faster render times between the new and the current VRay version. So specifically for this, I will immidiately kick out AMD CPU as a choice.
That Xeon should serve you for several years. I guess you are in the gaming industry, so you won't go very hard on rendering like me (I am in cinema VFX).
Also, I did not use Katana yet. So I can't really recommend anything for it.
But I would like to give you and advice - grab 30 bucks more and take in 16 gbs of RAM. Specifically since I got into dDo for texturing lately. (you can get a legal copy for free, but you need Photoshop, since dDo runs in PS's environment)
I did a bit of reorganization. I put 60 GB SSD instead of a 120 GB and 16 GBs of RAM instead of 8. I think this might help you.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Xeon E3-1230 V3 3.3GHz Quad-Core Processor ($284.98 @ Newegg Canada)
Motherboard: ASRock H97M Micro ATX LGA1150 Motherboard ($42.90 @ Amazon Canada)
Memory: Corsair XMS 16GB (2 x 8GB) DDR3-1333 Memory ($154.88 @ Canada Computers)
Storage: Sandisk Solid State Drive 64GB 2.5" Solid State Drive ($50.38 @ DirectCanada)
Storage: Seagate Barracuda 1TB 3.5" 7200RPM Internal Hard Drive ($54.99 @ Newegg Canada)
Video Card: EVGA GeForce GTX 750 Ti 2GB Video Card ($139.99 @ NCIX)
Case: Zalman ZM-T1 MicroATX Mini Tower Case ($24.99 @ NCIX)
Power Supply: SeaSonic 400W 80+ Bronze Certified ATX Power Supply ($61.98 @ Newegg Canada)
Optical Drive: LG GH24NSB0 DVD/CD Writer ($17.95 @ Vuugo)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($99.79 @ DirectCanada)
Total: $932.83
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2014-08-06 19:04 EDT-0400
Cheers.