WinUAE is the best Amiga emulator out there, it gives you so many options to configure that beginners will find it terrible but Amiga lovers will worship it.
This emulator requires the startup roms(Kickstart ROMs) of the real Amiga and some disk images of Workbench(only if you wish to have a desktop enviroment). After the configuration you may "install" workbench and begin using your brand new Amiga!
