If your board uses the KT266A, KT333 or KT400, you won't see a huge performance boost, especially with that particular video card. Also, you wouldn't be able to take full advantage of the dual DDR controllers with only 1 stick of RAM--though that's not going to completely kill the performance of the board. If you want my opinion, I'd look into more RAM and/or a faster video card.
the thing is I could sell my board and get the other one half price, and I could try to exchange my ram for 2 sticks of 128. I know the video card is crap but it's also a lot more expensive to replace. I had other suggestions like the soltek 75frn-l, I was also thinking of the msi k7n2.
If you want a new motherboard, look at what options you want/need and go from there. Personally, RAID and LAN are a big deal for me, and that's what I look for in a board usually. Don't get a loaded board with features you won't use. MSI is a bit cheaper than Asus, but they're pretty solid as well. Asus is good, but you do pay quite a bit for their products. Again, I don't think you're gonna get a real significant boost by getting that board---at least that you can't tell by benchmarking.
I think you'Re right and I will keep what I have. I'm just pissed that I bought the soltek when I could have had better for less if I had not listened to the salesman and if I had waited 2 weeks. the soltek is good, it has no flaws but.... unless I get a great deal I'll keep what I have. there was a brand new a7n8x deluxe for 1$ on ebay, it did not stay at that price for very long though !