Flight Sim 2004 is more than enough for practising IMC flying. It's all I used in addition to my IR training, and I'd say it helped. It should be super cheap on Ebay, or download a torrent if you're into that sort of thing.
You will end up learning to fly a computer, which is actually far more difficult than a real aircraft, so I wouldn't recommend it for things like the actual flying of an ILS, the way I used it was simply to engage the autopilot, then use the on screen controls to move the aircraft to get my head around what the instruments were actually telling me, particularly for things like ADF tracking and holds.