Finding the right chipset for my acer veriton

Hello,

I am having a problem finding the drivers I need to put on this computer. My dad bought an Acer Veriton 5500G used with no hard drive. He then formatted a western digital 40GB hard drive and installed windows xp professional on it. When I tried hooking up my internet on it I realized that the computer did not have the drivers for the ethernet among other onboard features. I have a Maxtor DiamondMax 9 plus 120GB hard drive that I was going to install as Master and keep the 40GB as a backup, but this computer won't boot with my hard drive for some reason. (I read on one site that chipsets are what helps recognize larger drives). I installed my hard drive as the slave and it recognized it but do not have access to all of my files. I then connected to the internet through my link on my old hard drive and downloaded the drivers for a few of my devices that I could find. Due to exhaustive research online I believe that I need a chipset! In detail an Intel 845G. I am nervous about downloading the wrong thing and messing up the BIOS. Is there any advice that you could give me?