Defintely get the 7800GT, best video card out there for the price.
Mobo looks good, defefintely again go with the X2 3800+ dual core power !!
The el platinum revision is good ram for OC'ing otherwise you shuold just go with some nice corsair valueselect if you aint OC"ing
Antec truepower 550W power supply 80-110 dollars
OCZ 520W powerstream 120 dollars
Enermax 600W all in one noisetaker 150 dollars
Fortron 450W power supply 50 dollars
Those are all good psu's
Don't forget that now your build is officially