how to calculate possible Bitcoin-Mining revenue

Hello.

I am wondering if it would be a good idea to use a Tyan server
(e.g. a FT77A) with 4 GPU for mining Bitcoins (I am not sure if the FT77
can be populted with 8 of the newest/most powerful AMD GPUs)....

Question:
How can the Bicoin-mining performance of a system like a Tyan server
(e.g. a FT77A) with 4 or 8 GPU (the newest AMD GPUs) be estimated/calculated
(during 1/one day) ?


Any feedback is appreciated very much. Thank you!

John


PS
I don't know to what extent the GPU-performance estimation page of
Ivon Golubev(http://www.golubev.com) could be helpful for such a calculation...