Acid will probably do it fine, and if you already have it, I guess you could keep using it. I'd say Reason 3.0 is a nice all-in-one package (sequencing, a decent sampler, a subtractive synth, drum machine, etc) but perhaps it's overkill for you.
You sure there's no panel or such in Acid that'll let you configure the computer's MIDI input? And you DO have the keyboard's MIDI out going to the computer via your Midman, right? You need the keyboard to send MIDI to the computer, not the other way around.