don't know about driftwood, but it will probably make the aquarium cauking and anything plastic in the tank turn blue/green!
if you don't want the discolour, then instead of buying ich medication try useing 1teaspoon salt per gallon of water for 2-3 weeks, and raising the temperature a few degrees. this should help, but I don't know what kinds of fish you have, so you may want to post that. some fish hate salt and it may harm them, but only 2-3 weeks of it to cure ich should do more good than harm.
salt is cheeper than meds and in my oppion works better