jerry has some 40g oceanic sumps for sale. it should fit under your 75 stand. then i would get a good skimmer to put in the sump. along with some miricle mud and some feather calarpa.
i would also recomend going all out with your lighting from the start. otherwise you will pay double to upgrade later.
one question though, what do you plan to stock the tank with? that really helps determine what you need for equiptment. if its only a softy tank you could get away with
vho lighting. if its a stony tank than 2-250w mh system.
kalk reactor or ca reactor if its a stony tank also. its all up to you and how much you want to spend.
i just put together a 250w mh system for my 180. i used coralvue electronic ballasts. they are nice because you dont have to worry about what bulbs will fire off those ballasts. and they are reasonably priced too.
you might want to think about how you are going to return the water from the sump. sea swirls, squid, ect...
if you are not sure of what you want, i would wait and get some more info first and then start getting equiptment.
just remeber its your tank and your money so in the end its your decision as to what you want.
thats just my opinion.
scott L