CADSoft EAGLE is probably the most popular choice for hobbyists, and DIPTrace is another that seems to be a bit easier to use. Both have no-cost versions available for limited use. KiCAD is a Free Software alternative. There's a whole forum category for PCB/EDA tools, just scroll down a bit from the main forum page.
I've used EAGLE a little bit, and the interface definitely takes some getting used to, but it's very widely used, so there are lots of people who can help with it.