Are you able to get into the CMOS setup? If you are (with the dual core CPU) then great!!! It means your bios is v5.0 or later already installed.
If you are able to get your computer to POST, then you should be able to hit the "pause" button so the screen stops. The bios number will be posted on the screen.
But.... if you are unable to POST with that dual core CPU, it means you have pre-v5.0 installed.
I checked the chaintech website, and it does look like v5.0 is the first version to support that dual core. Link is HERE:
http://www.chaintech.com.tw/tw/eng/Download/dl_desc.asp?DCSNo=4&PISNo=318
Often there is a sticker on the motherboard that gives you the bios number, take a look on your motherboard for a sticker with AWARD on it, and see if you can find some numbers on there. I have found conflicting info on the web. Some say that AWARD will put the stickers on the board, but others say that PHOENIX bios stickers have nothing to do with the bios number, it is simply a sticker counter. (I believe Phoenix and Award are the same company).
Anyways, if there is an AWARD or PHOENIX sticker on your motherboard, do a google for the numbers it gives, and hopefully that will tell you what bios is installed. If there is no sticker, then I am afraid the only way to tell will be to pop in your dual core CPU, and if you boot up, you know you have v5.0 or newer!
If you are unable to POST, then your options are to either find a friend with a socket 939 CPU and use that to boot yours up, and download a newer bios, then replace yours.
Or to send yours board back, and get one with a newer bios.
(I am not really a pro on this type of thing so don't take my word here. Maybe someone else will come along and have some better news).