High Output Alternator, for a somewhat large system

Hello,

I have a 1995 Cadillac Fleetwood Hearse, with a 350/5.7 L engine.
I would like to put add a fair bit to the electrical system such as:
19" LCD TV
Original Xbox
Some extra lights

and
a 300 Watt Sub/Amp combo.

The TV, Xbox and Lights are hooked up to a 1000Watt Pure Sine Inverter.
The vehicle is also equipped with an AC unit, and two large cooling fans for the rad.

So it seems apparent to me that I will need to put a high-output alternator in, as well as a second battery.

I called a couple alternator shops and asked if they had any for the vehicle and one of the guys told me that there is no need for a high amp alternator and that it wouldnt do anything extra (he didnt speak english very well and didnt make much sense), and then told me to buy a "condenser or something, I think it is called, I don't know".

So, please offer any thoughts, suggestions or comments to this matter....

AND if you think the alternator is a good idea, if someone could show me a site for cheap high amp alternators, that would be appreciated too.