To say the truth, you cannot get That good circuit stimulating software free. You need to buy them. However you can try this Free Circuit stimulating software which I use. Click on "Click here to download the ZIP file (5.67 MB)"
I agree with the others--ExpressPCB is a good place to start, but don't get hung up on it if you plan to do more extensive wiring and/or PCB design. For that I'd recommend Eagle, KiCad, or DIPtrace. All of them have free versions.
If it's a simulator you're looking for, try LTSpice, from Linear Technology, like ErnieM suggested. You can also get free trials of Multisim, which is actually my preferred simulating software (right behind Proteus ISIS). However, both ISIS and Multisim will require you to purchase the software if you want to keep using it after a certain amount of time.