Ted,
You know that the free version is only okay to use for non-commercial applications, right? Also, it only does 2-sided boards, and the max board size is 4x3.2 inches (100x80 mm) and it only does a single schematic page, no multi-page or hierarchical schematics.
Don't get me wrong; I'm very productive in Eagle, and it was the first program I recommended up above, but I think it's important to call out the limitations.
After reading the other recommendations in this thread, I've taught myself KiCAD, which seems to be the best free linux-compatible schematic-and-PCB tool you can find. It also runs on Windows and MacOSX. It does any number of schematics, it does hierarchy, it does any number of layers and any size board, and you can use it for things you sell or otherwise utilize commercially. If you need anything beyond the limitations of free Eagle, you have the option of paying > $600, or re-training on KiCAD or something similar. You might as well start training on KiCAD from the beginning 