Upgrade confustion !?!

I am a little confused about all this new technology coming out, so here is the stuff i am going to buy for my upgrade in a few days.

cpu -
AMD Athlon 64 3000+ Retail

mb -
KV8-MAX3 retail

ram -
this is where i am confused. The board says it supports 2100, 2700, and 3200 speeds. So I already have a 512 stick of kingston hyperx 2700 so will this work? And will my system run at full speed or what? Will it run faster with a stick of 3200?
The second part is that the board says something about single sided memory or something along those lines. What kind of memory do you recommend and how can i tell if my current stick is single or dual. And that only some ddr slots support some sticks.

any info will help very much. thanks.

Supporting AMD with your breakable stuff.