Hi Ioannis,
Have you used the ISD chips much? I have managed to write some code for the the isd4003 with SPI control about 18 months ago, but since then that type has been discontinued in the UK. I have got some of the 1700 series chipcorders and have been playing with them in push button mode. The problem I have with them is removing the pop and hiss that that is in the back ground when in play back, if I could remove or attenuate it they would be fine for my application. I found this last week when searching for ideas, it uses the audio out and parallel port for control.

www.fragtag.com.au/ISD_recorder.htm

Which makes them more appealing, like I said if I could remove the noise i'd be using them.
I have the circuit built as per the data sheet, with an lm386 audio amp connected to the speaker output. If you have any ideas they would be great.

regards Nick