Well, I just built a maya machine a week or so ago. Ill tell you whats good. The video card I have is a GeForce 7950 and it's great for maya. On the box it says it's meant for 3d as well. I recommend that one. You can get it on www.newegg.com for about 279.99$. I have 3 gigabytes of ram which is great but 1 or 2 will do. For hard drive you might want a faster one with more gigs because maya projects and maya take up alot of space. For proccescor I got a 2.4ghz E6600 from Intel. I would recommend getting a higher one but thats just me. I'm not an expert on computers but I got some help from computer nerds to pick out the parts for 3d modeling.
Good luck