chainring question

Just a quick one here. I have this old MTB that I have been riding and
have added a few new upgraded parts to. The next thing I think I would
like to do is change the chainrings, it has a double on it now I don't
think I want to change it to a triple but might like to change to a
more road type setup. But the problem, well not really a problem, but
it has the ashtabula style crank, and I might like to keep that style
just because it is simple to service and they tend to last a long time.
I have heard of a "power disc" that would let me bolt on higher quality
chainrings to the one piece crank. I found one he
http://www.bikepartsusa.com/product_...tml?p=01-97938
And from what I can tell from the picture this would seem to fit the
bill as far as being the go between part to go onto the crank and then
onto the new chainrings. Is this right?

Ken