Gena, rendering is slow and every body have to deal with that, just as the web surfing is.
Before spending such ammount of money, drop 1.5 GB of ram in to your computer. Then if you need more speed you can get another computer later, but what takes time is the design more than rendering.
I preffer to have 2 dual 500 machines (each under $1000) with full ram than one dual 1GHz. When one computer is rendering I can work in the other one.
I may even do a net work rendering!
That is it, all for less than the price of a dual 1 GHz.
And do not fall in to the fever of getting the latest mac. If you go to any post house they still having 400 Mhz mac with plenty of ram.