I am about to shoot off to craplins to get a 2.5-3.5 adapter... I am unsure as to whether I will be happy wedging a 3.5 drive into the Falcon, but I do have a few Compact Flash adapters that should run just fine... If anyone knows better, then tell me.
one of those and the CF Card, and the Adapter wont take up any more room than a stock 2.5" drive anyway, so I would be ok with that I recon.
I would however, prefer a proper 2.5" - 2.5" cable and use a real 2.5" HD, but there you go!
RE: Falcon : Internal IDE issues 