OOoops sorry that's about 4 motherboards out of date I'm here now :-
DDR2 - Gigabyte GA-EP45-EXTREM
DDR3 - Gigabyte GA-EP45T-EXTREME
I've no experience of that board but did consider the
Asus P5E3 Premium/Wifi@N Intel X48 in my experience the Lifestyle boards seem to out perform the ROG boards. I went for the
Gigabyte GA X48T DQ6 instead which proveed very solid, the only slight drawback was the relatively simple
bios which is basically as your current board the x38. The current crop of giogabyte P45 boards have now got a more feature rich
bios (see the Extreme limks) and in my opinion better value than the Asus X48 boards, which are very pricey >£200.