Thanks for the quick reply. From post 4 I was able to successfully update my device drivers with no problems using the zip file (the updated 2680 drivers).
I think my issue seems to be that I don't have the 2681 drivers on my system? When I go to update the drivers and uncheck on the show only compatible hardware box, I still cannot find the 2681 drivers.
I was under the impression that the installer package that won't open is what installed these drivers for me so that I could select them. Should they be on my XP system already? If so, any suggestions on how to find them? It's XP Pro 32 bit, and I did install and update the boot camp drivers to the latest version (hopefully that is not a problem).
As far as grub, basically I performed a normal install of it with Ubuntu and it resides on my linux root partition at /boot/grub. After the normal install, when it was up and running and would boot linux or Windows properly from the grub prompt, I backed up and replaced the stage1 and stage2 files with those that you provided. Everything will still boot correctly, and I imagine I am in AHCI mode for Windows, though the installer package still won't open, nor can I locate the 2681 drivers...