Okay, I have noticed on a lot of forums on this site and elsewhere that people are having problems installing in AHCI mode under winXP with the GA-EX58-UD3R. I had the same problems - here is how I got round it.
If using a dual-boot system make sure the first hard disk, partition 0, is where you will store WinXP to.
Create the floppy driver disk as explained in the instruction manual. When running the software from a command prompt you get four options of driver disk to create - which one you choose depends on whether you are using the Gigabyte SATA sockets or the Intel SATA sockets on your board. Make the appropriate choice. This is explained reasonably well in the manual.
Install as you normally would, pressing F6 when it asks if you want to install SCSI or RAID drivers. It will then continue to load several more files before stopping again.
At this point it will ask you to press 'S' to install from a floppy. Do so. You will be presented with a list of four drivers from the floppy disk, none of which are suitable for AHCI. This is where people go wrong. They choose one of the four drivers and the computer then crashes. The AHCI drivers are on the disk, but you must scroll up (not down) to find them. Keep scrolling up using the cursor keys until you find the Intel 10R AHCI drivers. Then select these. They will be loaded up, and you will be asked if you want to add more drivers. You don't, so continue by pressing enter.
The installation should proceed as normal. If you have installed winXP on anything other than the first partition of the first drive on a dual-boot system the installation will not work.
So that's it.
The good news is that Vista installs perfectly without these shenanigans.
Hope that helps.
