marine newbie please help

Well I must say that saltwater is much harder than freshwater. First, any good quality live rock that has been pre-cured is good. Fiji live rock is good. As far as your set up goes, if you are usings a hang on the back filter, because that what I assume a piggy back filter is, then you dont really need a canister filter. Those things just accumilate too much nitrate and and if you have live rock, a good power filter, and a good skimmer. That should be all that you need for a 55. As far as what fishes to go with, start off with a few damsels. They are very inexpensive, and if something happens to go wrong with your tank, your pocket wont take a beating. Saltwater fish can get expensive. Just make sure that your tank is fully cycled before you start to add livestock, it will cycle just fine with the live rock.

Lokis,
I wouldn't say salt is much harder than fresh, it's just more labor intensive... oh yeah, and it can be alot more expensive. I nearly went into cunvulsions the day I bought my first installment of live rock. Sand, rock, lights, skimmer, power filter, all the Bio Stars, resins and Purex, $$$, are far more intimidating than just the "Harder to Maintain" philosophy.
Don't get me wrong, I am totaly gaga over the mini reef I've started in a 55 gallon setup. My Banner, Flame Angel and Maroon Clown (w/ Bubble tip Anenome) are really cool to watch interact, and the small feather dusters and such really satisfy... my kids love to watch around feeding time.
Time and care is part of the fun, enjoy it!

RM