Dell 370 or 470?

Basically Im looking for a new "home" PC.

This PC would be used to run Autocad and Inventor in
"training" mode only...... no real production work or
assemblies with thousands of parts. Basically Id use it
at home to "play" around with Inventor.... learn it

My other intended uses might be something to run voice
recognition software on such as Dragon Naturally
Speaking. see link

http://tinyurl.com/2c6aq

Having said all that I was thinking maybe a Dell 370
with a single Xeon cpu and 1 gig ram might be a good
fit for above uses.

Or do you still feel it best to get a dual cpu system
such as the 470 even if I only get one cpu installed in
it for now?