Linux emulator

If you mean can you get a layer that lets you run Linux applications on Windows then the answer would be a sort of yes. Normally if there is demand open source projects get released as native windows versions. There are tools such as Cygwin which give you linux commands and the libraries but applications would normally need to be compiled against these to work properly.

If you want to run windows but still run the odd Linux application you can install virtulisation software such as VMWare and run full Linux distributions within them. In simple terms it would let you run Linux almost as an application.

The nice thing about open source is that you have the code and can always modify it to whatever platform you want.. providing you have the skills (which does rule me out!).

VMWare is very cool as AudioVoodoo and evongugg have indicated.

cygwin is also very nice and incredibly useful but will not give you a native Linux environment, it does approximate a Linux / Unix environment.

There is also QEMU

http://qemu.org/

There a few other options but they are not as good as VMWare/QEMU/cygwin.

QEMU and Cygwin are both legally free and open source.

VMWare Server is legally free for internal use.

GL :-D