Iris and Nettle2 BIOS Update Compatible?

[DetnnoSound]

Hi, first time user with what I hope is a relatively simple issue. I wasn't sure where to post it... I hope this is ok.

I have an old Compaq SR5110NX that I'm trying to rebuild. Currently, it's running a stock Athlon 64 3800 with the MCP61PM-HM Iris-GL6 Rev. 1.0A motherboard. Not the Iris8, which seems to be a direct sibling of the Nettle2, if I'm understanding what I've been reading correctly.

The BIOS is Phoenix Tech, rev.5.09 dated 05/03/2007, and here-in, I think, lies the problem. More on that in a second.

I purchased an Athlon 64 X2 4800+, which is the max default recommended processor this board can support. However, after I installed it and powered on, I got a "Not compatible" error.

Now, I assume this is an outdated BIOS issue... but the installer for any updated BIOS can only be run in Vista, and this system is running XP. I found the Nettle2 BIOS flash that can be done with a USB and DOS to bypass this, but is that compatible with this board, since it's older? Or is there something else I should try?

Any expertise would be greatly appreciated! Thank you!