Bochs is a powerful x86/amd64 hardware emulation and debugger software. Besides the CPU and instruct set extensions, it simulates common PC/AT hardware, an ISA and PCI system bus, memory, disks, video hardware, ethernet, and enough of a compatible BIOS to run DOS/Winows, Linux/BSD, Minix and other operating systems. It doesn't provide virtualization, thus runs extremely slow, but is safe to run for the host operating system.
Wine is an implementation of the Windows API on top of X and Unix. It does not require Microsoft Windows, but can use native Windows DLLs if they are available. It provides both a development toolkit for porting Windows source code to Unix as well as a program loader, allowing many unmodified Windows programs to run on x86-based Unixes.