I ride a 2005 giant Iguana also and like it a lot. Most components seem the same except for 100 mm
travel marzochi exr shock and truvatativ powerspline bottom bracket. It also has a square tubing in the frame. If you are a bigger rider you may bottom out the 80 mm shock and wish you had a different shock.
Ask your dealer to compare the bikes and the differences of two bikes. this would be a good question to ask in the " around 500 dollar mountain bike thread".