Sweet! I haven't been in a doom forum since i left Doomworld.com, i was in Doom3world.org but it became politics3world.org. Good to see a new one.
Use http://dengine.net/. All you need is the original game files, which you put in the specified folders, and you can play just fine. Even use mods, mouse input (after using Doomsday for nearly 2 years now, I can't live without the mouse), and other stuff. Its very easy to use also.
If you can live without the eyecandy, i would rather recommend http://zdoom.org, it feels closer to the classics, and you can make it work exaclty like the originals (no z-axel, 320x200 resolution, all the original bugs

).