I am using the following software:

PCB-Design:

EDWIN-XP (www.edwinxp.com)

Simulation:

• EDWIN-XP
• LTSPICE  (http://www.linear.com/designtools/software)
• LogiSim (http://www.cburch.com/logisim/index.html)

Mechanical:

Autodesk Inventor Ultimate Design Suite (www.autodesk.com)

And probably the best software ever created, VISIO

http://office.microsoft.com/en-us/visio/