I would highly recommend using a quad G5 Macintosh running OS X to do any 3D work as they are highly customizable and very powerful. However if you must have a Windows machine there are a few decent options.

The Dell 710 H2C is very good for 3D work. They come with a new Core2Extreme processor at 2.66GHz. This is about as good a processor as your going to find. Your going to want as much memory as the computer with allow. The 710 comes with 2GB standard, but you should really upgrade this to the max (4GB) as this will greatly cut down on time wasted by rendering objects. The 710 comes wiht a 500GB hard drive, which will be more than enough to get you through. You shouldnt need to upgrade the hard drive, but if you do run out of space you can opt for an external unit. It also comes with a 20" widescreen monitor, but you should really up that to a 24" monitor to allow more tool pallets and other windows open on the screen and work as large as possible to help with textures and lighting.

The overall cost of that computer will run you $4700. If you plan on actually running your own 3D studio, you'll want to spend good money on the computer. At $4700 your getting a very high performance machine. This computer is configurable with a few video card options. Choose the best one you can afford, but I wouldn't overkill it as the video card only controls showing the objects your modeling in real-time.

Autodesk Maya complete is going to run you a hair over $2000 once taxes and shipping are calculated.

This puts you up to $6700 without whatever cameras and cables you plan on purchasing.
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