There are some other threads on this topic which it's worth looking at for good advice. I'm no expert on this but this is my my point of view:
Zoom devices are pretty good - I have the H4 and I get fairly good results. But I get better results since I've bought an interface (the Apogee Duet, which is a specialist Apple Mac interface) and a matched pair of condenser microphones. I bought condenser microphones because my research (searching Delcamp and Googling the web) suggested that people find them the best option for the classical guitar. The only thing you need to watch is that condenser mikes require a source of power, so you need an interface that supplies what is called 'phantom power'.
Eric from GuitarLoot
Renaissance and Baroque freak; classical guitars by Lester Backshall (2008) and Paul Fischer (1995)