How sophisticated do you want it to be?
Are you willing to pay, or do you just want something shareware/freeware?
Personaly I just started using the free version of Eagle from CadSoft.
This thing is great. I wish I could afford to get the professional version. I might shell out for the Non-Profit license sometime, since I don't do this commercially.
Freeware prog. don't need to be too advanced, shall just create schematics to show at the PC, no printing. Looked at the Eagle CadSoft page program, but it looks like the ftp is offline.