No problem. Fair enough.
Just wanted to present an option to consider....
What you do need to do is learn about the 3d graphic software applications you will be using and what system requirements are needed to support that software.
To "last awhile" you will need to exceed those specifications or be sure to plan for growth within your system.
Plan your build to meet the specifications, check the cost against your budget, then "upgrade" your build with some future proofing: faster CPU/GPU, more RAM, larger drive, etc..
Start with this link in this forum:
http://www.tomshardware.com/reviews/build-your-own-pc,2601.html