Hey Fabiano,
I am somewhat new to underwater photgraphy (2 years) and owned the DC500 that you are referring to. I actually owned the camera with (2) strobes, macro lens, and wide angle. I have since switched to a digital SLR.
I was perfectly pleased with the capability of the camera and was able to take some real nice pictures (for my taste as an amature). A friend of mine bought the rig from me and has a renewed zeal for diving especially with his camera. 
As far as the digital zoom portion, I'd go thru the set up menu and disable digital zoom. It only degrades the image. I usually shot the picture with out any zoom at all for best results. It is very small and compact w/o the strobes but I highly recommend getting at leat one strobe but preferably two. Just in case one breaks down as it has underwater, you'll at least have a back up! Get the one with the adjustable output which is a bit more expensive but well worth it. One thing to keep in mind is the longer charge time for the strobes (up to 15 seconds) but it might have beeen a result of the batteries I used.
The video on it is a really nice feature especially in warm water enviornments. That is one thing that I sorely miss when I switched to an SLR.
I also had the macro and wide angle lenses. I really liked both but especially the macro lens kit with 16x magnification. It's actually for the previous model cameras but it surprisingly works well.
Overall, I highly recommend it to a novice underwater photographer. I loved it and that gave me a purpose when I went diving. I love diving and I love photgraphy and the both combined is highly adictive and like nothing else.
Hope that helps.