Started mining with minerd 1.5 days ago.  I have mined a grand total of .017 DGB.  Either my computer is in a class of low-end I can't quite fathom or I am doing something wrong.  Or both.

My minerd command line:

minerd -t3 -o stratum+tcp://s1.theblocksfactory.com:9004 -u catman.1_device2 -p

Any advice for the rank greenhorn here?