Hi, this is my first post on this forum.
What BIOS version are you using? If it's 1.3, you might be able to fix your problem by downgrading to version 1.2.
I built a system using the A8N-SLI Deluxe shortly after it came on sale here in Japan. I used a pair of Maxtor 7B300S0's for my data, and a fairly new 120GB Maxtor IDE drive (recycled from another system) for my Windows XP and software installations.
It worked fine for a while, but when I tried enabling NCQ on the SATA drives I quickly sufferred massive data corruption, so I had to disable it and reformat both drives. I would therefore recommend avoiding NCQ like the plague until this issue is officially acknowledged and fixed by a future BIOS version.
A few days ago I upgraded my BIOS to version 1.3. It worked fine when I rebooted the system without turning off the power. However, last night I tried my first "cold" boot, and it hung while booting Windows. I tried rebooting multiple times, and noticed that it spent a while searching for IDE drives, didn't find the 7B300S0's, then hung just after displaying the Win XP splash screen. When I disabled the SATA controllers in the BIOS, or disconnected both SATA drives, it booted OK. I also discovered that the Silicon Image controller could recognise the drives when I plugged them in to its connectors, so I figured that the drives were OK.
After a while I suspected that the new BIOS was the problem, and rollled back to version 1.2, after which it worked fine.