Newer SVNs of NullDC support dinput, and even xinput if you have a 360 pad connected (or you can even use x360ce to emulate an x360 pad with a standard usb joystick and then use the xinput plugin, if you don't want to dick around with button configurations).
As for the hardware, NullDC is not as demanding as PCSX2 or dolphin, I remember being able to run 1.6 on a core 2 duo 1.8ghz with an 8400gs videocard, but the newer revisions (which is absolutely recommended for compatibility purposes) have increased the requirements a bit. I have 2.5 ghz wolfdale PC with a 9500 GT videcard that can run games just fine, even with the internal resolution set to max supported (awesome for polygonal games, but introduces tearing and glitches in 2d games).
You can also use
Quickplay as the frontend, but you'll have to do a little bit of
messing around with the settings(but so far, it supports every emulator I throw at it, there is even a way to load PC games and an instance of SSF that automatically mounts images using batch files).
There is no reason to take on a project like this, yet I find myself doing stuff like it all the time 
