need advice on new build

Im in the process of doing a new build and need advice on memory.Im not looking to build a high end gaming machine but may play some games down the road.
So far I have purchased :

MOMBO - M4A785TD-V EVO
CPU - AMD Phenom II X4 925 (AM3)

Looking for help on purchasing 4gig memory that wont break the bank ( thinking around $150 - $180 ).

Im just confused over the diffrent specs 1600,1800 etc.

Any advice on my memory purchase?

Also plan on buying the Ultra LSP750 750-Watt Power Supply and running windows 7 64bit

thanks to all that reply

-Bryan

Well, the 1600/1800 you're referring to is the speed. for the everyday user the basic 1600Mhz would be fine for you! And anyone else really.

This here would work fine.
http://www.newegg.com/Product/Product.aspx...0-435-_-Product