Research different methods of filtering a saltwater tank and they will dictate what equipment you will need. No matter what method, skimmers are always nice.
I use sumps and employ the Jaubert method in the sumps, with a skimmer at the beginning (modification from Jaubert) and usually in with the plenum I have chaetomorpha to help reduce nitrates more that just the deep sand bed and plenum would.
Then in the main tank I use 1-3 pounds per gallon of live rock and a flow rate around 22 times the volume of the tank (other than my SPS tank which is closer to 33 times the volume in water movement per hour). Koralia make some nice and cheap powerheads that are just wonderful. SEIO is also nice and cheap.
That is it. I never have nitrates or other issues with water quality.
In a 75 gallon you are at the minimum for many wonderful fish.
A school of flasher wrasse are amazing in the medium to large tanks and will put on flashing displays and really showcase vibrant and wonderful colors. In fact most wrasse are quite stunning. They also bury in the sand to sleep which is just so interesting to me! You will need a medium deep sand bed in the tank, enough to allow the wrasse to bury at night. Some wrasse can be sensitive and are probably not the best choice for beginners, but I have always had great luck with them (get a lid they do jump).
Dwarf angels are always very personable to their owner and can even be bred and hybrid in captivity, but care must be taken as many do not like other angels. The lemon peel is always a nice bright choice. They can breed with the half black and other types of closely related angels and make stunning hybrids. (Something to think about in the future, but difficult for beginners and even most experts have trouble getting any angel to breed in captivity, but worth thinking about) Rusty angels are also very nice, and of course the more common flame angels are very bright.
Some smaller species of the regular size angels are also nice but usually less tolerant of other angels. I love the flagfin angel, for example. I have found them to be hardy, and darling! They are actually referenced as difficult to care for, but with the new frozen angel foods with sponge in them, there is not a real issue. I also adore the Rock Beauty, again I am always shocked they are listed as "difficult" as mine has been with me for many years and gone through several tank crashes at the beginning before I learned the Jaubert and other useful filter systems (I used to have a canister filter and hang on back biowheel filter and had a few crashes in my day) and has always done well. Again, with the angel foods and live rock, old nutritional limitations no longer apply.
A good book that talks abit about breeding and different angelfish:
http://www.amazon.com/Angelfpricey-Butterflyfishes-ScthemW-Michael/dp/1890087696/ref=sr_1_9?s=gateway&ie=UTF8&qid=1285882888&sr=8-9
Now if you do not feel up to some of the fish I reference above because they are pricey and some consider them challenging, start out with a nice school of reef chromis. They are similar to damsels, but lack the aggression. They are often some of the cheaper fish but are still colorful and make a nice school. The blue/green are the more common ones, and the cheapest. The vanderbilt Chromis are a little more expensive and harder to find, but still peaceful and much brighter. The blue chromis (Chromis cyaneus) are very nice blue and black fish that are a bit pricey for a chromis but again very nice.
I looked up some more on liveaquaria, and here are some other peaceful chromis to think about, including the ones I referenced:
http://aquarium-fish.liveaquaria.com/search?p=Q&lbc=liveaquaria&uid=816819669&ts=results&w=chromis&af=temperament:peaceful cat1:marinefish&isort=score&method=and
PJ cardinals are another hardy and friendly fish that are not too hard on the pocketbook.
http://www.liveaquaria.com/product/prod_display.cfm?c=15+26+85&pcatid=85
If you want larger and hardy fish, think groupers and triggers. You cannot put more than a few fish in the tank, but they are extremely hardy and very personable to their owner.
When deciding on fish, the PocketExpert Guide to Marine Fishes was invaluable. Get it and enjoy picking through the fish. It gives the basics for hundreds of species, lists their difficulty level, etc.
http://www.amazon.com/PocketExpert-Guide-Marine-Fishes-Essential-/dp/1890087386/ref=sr_1_1?s=gateway&ie=UTF8&qid=1285882651&sr=8-1
Enjoy!!!