Designing a complex circuit board is much easier these days thanks to specialised software. Here's a few of the more well known offerings as well as some other information to make designing a board easier.
Altium (formerly Protel)
- Altium Designer Professional, but expensive.
- Altium Designer Viewer To view all Altium files.
- Autotrax Old DOS version, now freeware.
- Easytrax Old DOS version, now freeware.
- Design Spark PCB Free.