If you are just planning on plunking everything you have into a new motherboard, forget it. You won't see a difference. The P5W DH Deluxe is a great board (I should know, I have one). You may see some slight differences in synthetic memory benchmarks, but it doesn't translate to real world performance increases. The only real reason to switch would be if you were running CrossFire and you wanted the warm cuddly feeling of running your cards in X16. Your not, so there is no real reason to spend the money. As you said, your not much of a gamer.
If you overclock, the P5W should do some mid level overclocking, I have my FSB at 370. I haven't experimented with trying over 400 (975 has known FSB holes in there straps), but I'm sure it's doable.