Are you editing SD (Standard Definition) or HD video?
What you have is never going to do very well with HD video... except maybe HDV from a tape camera
I post 3 possible price levels in http://www.pacifier.com/~jtsmith/ADOBE.HTM if you build your own
For now I'm just editing SD to update my demo reel, but I would like to edit in HD as well, especially using my After Effects software.
For HD, the minimum I would recommend is the "medium" build at my link... if you plan to overclock, build with the 3770k CPU not the 3770
That is, of course, only MY idea... I list an Intel motherboard, ASUS is another popular brand... I have used both brands, with equally good results
Adobe's MINimums http://www.adobe.com/products/premiere/tech-specs.html
This message has a really good graphic about requirements
More about Requirements http://forums.adobe.com/thread/618058
Disk Configurations http://forums.adobe.com/thread/878419
Really Great Pic in #3 http://forums.adobe.com/thread/1100383
Build a Desktop Video Editing PC
-what PC to build http://forums.adobe.com/thread/947698
-2 how to build videos http://forums.adobe.com/thread/1104182
-another video http://forums.adobe.com/thread/1145366
-planning & Building http://ppbm7.com/index.php/intro-part-1
-memory for LGA2011 http://forums.adobe.com/thread/1098759
-an Adobe FAQ http://forums.adobe.com/thread/878520
-several more links http://forums.adobe.com/thread/815798
-build tuning http://ppbm7.com/index.php/final-results
The FAQ section contains numerous articles that will answer most of your questions, like practical requirements, suggestions for building a PC in different price categories, etc.