RAM speed incorrect

[Milosenpotion]

I got a new computer and everything works fine, except the RAM speed isn't showing up right in BIOS or CPU-Z. Here's the RAM I have:
http://www.newegg.com/product/product.asp?item=N82E16820145034
It should be running at 800MHz, but when I check BIOS/CPU-Z it's showing up as 400MHz. When I go in the BIOS to the area for changing the RAM speed, there is a list of a couple different speeds: 400, 533,667,800, 1066. Is it safe to just select the 800MHz option? Or do I have to do some kinda overclocking or something with the voltages?
edit: This is my mobo, with latest BIOS:
http://www.newegg.com/product/product.asp?item=N82E16813131045

[Zogo]

AFAIK it's safe..lots of things are underclocked by default.

some guy I know was running his 600-700mhz cpu at 300mhz for like a year and wondering why his machine sucked.

[Janus]

excellent choice there milos.

check cpuz to see if it is running at ddr2-800. I know with regular DDR that it shows as half (for instance running at 200fsb is actually 400) where with DDR2 I think it is 200fsb is = to 800mhz fsb (I could be wrong)