Really dumb noob memory question

Which ASUS P43 board? P5P43TD PRO?

That board can accept 1600(O.C.)/1333/1066/800 Non-ECC,Un-buffered Memory.

Although you'll get better performance with faster RAM, I think that the consensus is that it's pretty unnoticeable between 1333 and higher speeds and 1600 costs a premium whereas there's no much of a difference between 1066 and 1333. I think that the best value is the 1333.

Tom's hardware recently published a series of informative articles about DDR3 memory. The DDR3 1333 modules appear to be the best bang for the buck. Go to the home page and scroll all the way down to the section at the bottom of the page with links to recent articles about DDR3 memory.

I would get something like this
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

For any ram you are considering, do your own homework.
Go to the ram vendor's web site, and access their configurator.
Corsair, Kingston, Patriot, OCZ and others have them.
Their compatibility list is more current than the motherboard vendor's QVL lists which rarely get updated.
Enter your mobo or PC, and get a list of compatible ram sticks.

Here are a few links:

http://www.crucial.com/index.aspx

http://www.corsair.com/configurator/default.aspx

http://kingston.com/

http://conf.ocztechnology.com/index.php?c=1

http://www.patriotmemory.com/configurator/index.jsp

Cpu performance is not very sensitive to ram speeds.
If you look at real application and game benchmarks(vs. synthetic tests),
you will see negligible difference in performance between the slowest DDR2 and the fastest DDR3 ram.
Perhaps 1-2%. Not worth it to me.
Don't pay extra for faster ram or better timings unless you are a maximum overclocker.

I would move up to a P45 board and DDR2 memory. Timings will be better compared to DDR3. You only need DDR3 if your going i7.

Alrite thanks for the help. I just wanted to make sure i could start up the computer with no problem if I put in a stick of 1333 ddr3. Just so many out there that i was confused as what what compatable with what.