Yeah, I realise what I'm trying to do isn't easy but better to have tried and failed and all that 
I don't the part number here at the moment, the datasheet is at uni, but we wanted something similar to this:
http://www.national.com/ds/DS/DS0026.pdf (which unfortunately is now obsolete).
I'll post the datasheet of the one we've bought first thing tomorrow morning.
Yeah I only bought the minimum spend at first to try and get one working on a breadboard. If all goes well, I'll order the rest of the components, enough for 6.