CPE is a great CPC emulator that is almost 100% perfect as claimed by the documentation. Free source code is available for portability (and where are the ports at, eh?)

NO$CPC, by the author of NO$GMB, is the latest word in Amstrad CPC emulation. NO$CPC has very low system requirements, includes a built in debugger, and is probably the only CPC emulator that has a chance of receiving an update any time this year ;-)