It depends. How is that for an answer? Let's start with attic power vents. If your attic is vented properly, you should not need one. If your attic is improperly vented and you install a power vent, you might suck a lot of your shiny, new conditioned air out of the living space into the attic and then outdoors. Power vents are easy to sell. It sounds simple, but so somple. Most of them are a waste at best and they can be quite harmful at worst.

Keep the whole-house fan? If you live in a humid environment with a measly diurnal temp change, get rid of it. You will cool slowly and load up the house with moisture that just needs to be removed before the house can be cooled the next day. If you live in a dry environment with a good drop in night time temps, keep it.

Where is your intake air for the whole-house fan? If you don't open enough windows and doors, you can back draft your combustion appliances, beware.

yep...depends.
where do you live?

I meant to include that sealing up the attic might be the best approach if you have or plan to put ducts up there.

Thank you for the input.

To answer some questions, We live in central NJ.
This is our first home, so pardon the ignorance. We really have NO idea what we are doing. I have no idea whether the attic is well ventilated or not.

All the AC ducts will be rung through the attic.

I looked at the whole house fans and attic fans and after a lot of reading determined that they tend to suck out the cold air and really are not that good. I think they are a hold over from the old days before central a/c.

Get some more quotes. Only two quotes does not give you a good range of companies to look at.

I think you should get get rid of the whole house fan. If you used it at night you would pull in humid air which counter acts the work done by the AC. I also think it creates heat loss in the winter since the fan is typically not well insulated.

I believe the powered attic fan does help if the attic has adequate ventilation. It helps lower the attic temperature in the evening.

I am also in central NJ. If you live in or near Mercer county I can recommend a good Carrier deal that I have used.

I'd keep the whole house fan and use it on the days where you know it works best. I would then put in a multi-head mini split heat pump. Skip the duct work. Look at Fujitsu.

If you do go with the ducted system DO NOT pay for it until you have a third party do a pressure test on the system. Typical residential systems loose between 18-42% of their energy in duct losses. The mini-split heat pump will give you high efficiency net to the space. It will do both the heating and cooling for your home.

What kind of heat do you have now, ductless? Jackfre makes a good point about having the new ducts tested. Does anyone know what the industry standard is for new duct leakage? In addition to that, keep in mind that what does not leak now, will in the future. Ducts outside of the living space are a bad compromise. When you get a leak in them, you add a power vent to your house. If in a supply duct you blow air out is one spot and suck it in in unpredictable places. If in a return, you suck air in from around that and then blow it out from leaks in the house envelope elsewhere. If you don't have returns in every room or other means of air return, you get pressure differentials between rooms that do the same thing.

The trouble with those whole-house fans from the 50s is that they typically let a lot of air leak by when not in operation. The shutters don't seal well. You really need something like a Tamarack. I question the utility of a whole-house fan in NJ. I won't dismiss them out of hand because they can be useful in the right climate.

A good source of information about what to do for you house might be your local land grant university. They typically have good, climate-specific information for homeowners. You could also try the adjacent states, Penn State, Delaware, NY (Cornell). Building Science Corporation (www.buildingscience.com) tends to be more technical, but I think it will be useful as well. Since it is meant to be nationwide, you have to zero in on your climate and weed out all the stuff for other areas so it is more time-consuming.

Power vents suck. They can be a good band-aid for a bad attic, but often not even that.