The original Doom, Doom II: Hell on Earth and The Ultimate Doom do not run on Windows 7, due to incomplete MS-DOS support, and the total lack of a 16-bit subsystem on 64-bit versions. Doom 95 will run on Windows 7, but suffers from numerous bugs. Doom 3 will run fine on Windows 7.

Note that the original DOS versions of these can be played in DOSBox. There are also ports of the Doom engine to Windows that will allow you to use the original data files from the DOS version, with essentially the same gameplay.