Re: Building new computer?
Well, technically, you don't really need the dual core. A regular Athlon 64 will do you nicely, but dual core does have it's advantages. Mutiple core allows true multitasking to exist between different applications at the same time, creating a more efficient processing solutions. In 2006, expect dual cores to dominate the market. It's new and it's nice to know that you have something that will keep up with technology.
I'm not familiar with your engineering programs, but if it involves a high amount of mathematical calculations and intense processing work, the more memory the better. Also a good CPU too. I would bump up what you have for an Athlon 64 X2 4800+.
*Fact: Microsoft Window's Blue Screen of Death vs Computerforums.org's White Screen of Death. Which is worse?