(I don't yet use Windows 7, so I have no idea how any of their players stack up.... but for 10-15 years I have felt that 3rd party programs, properly vetted, usually had more features, better interfaces and were less subject to security problems than what MS provided.)

(I don't even care for the often touted Media Player Classic which, though not a MS product, just never felt as 'çomfortable' to use. YMMV)