Hey Porky,
First off Welcome to FTF's! We are glad you have come to us for help.
We still need more info before helping you out fully. Like, what kind of setup will this be? FO? FOWLR? REEF?
How will it be stocked? Lightly? Heavy?
For a sump, IMO, I would make my own out of a 20-55g standard tank. It is MUCH cheaper. I copied my DIY SUmp/Refugium off of GM333's thread found here:
http://www.fishtankforums.com/28-diy...m-project.html (DIY Sump/Refugium Project)
The size would depend on what you can fit in the stand. The bigger the better....
For skimmers, IMO, I beleive they are the most important aspect of filtration for any SW setup. IMO, I really like my Euro-Reef skimmer. It pulls some amazing "gunk" out of my reef. So nasty it almost make me sick when I empty it! No lie....

These of course come with a heafty price tag.
A good knock-off of ER style skimmers, would be the ASM line of skimmers. For the money, you cannot beat their performance. A few other notables: Aqua C, Deltec, and Octopus Skimmers.
Octopus is made by the same founders of ASM, they have just moved on. Very affordable skimmers aswell....
Brad