Thanks everybody for your suggestions
We finally ordered the setup I said on my first post, with the difference the graphics card (we ordered an X1950 Pro instead of an 7600GS. Is it better than 7600GS?)
If we are lucky, then the PC would be ready by tomorrow
Too bad we didn't get a TV tuner card (but got that thing
) or that Asus lightscribe dvdrw drive...
Final Cost: 1700 Euros.