Reboot and select a proper boot device or insert boot media in selected boot device

After a couple years my custom builds' CPU was overheating. I replaced the stock fan/sink with that HUGE Cooler Master Hyper212+ and reconnected everything as before.

On first boot, I checked the BIOS and was relieved to see the new fan/sink doing it's job: 20*C. Hard drives are recognized; boot order is as before, but no Windows.

Hunting around for a solution on my back up system, I've seen a couple fixes that are not applicable (recognize hard drives? check.). I tried an interesting CMOS clearing technique (unplug - hold power button for 5 secs), but that didn't work. Somebody turned off/on their system 10 times and *poof!*, all is well. (?!)

Since BIOS shows all components present, I believe it's not a HW or cable issue. I saw something about a repair option over in the sevenforums group, so I thought I'd post here to see if anyone can suggest anything I can try.

Many thanks in advance!

Edit to add:
OS: Vista Business OEM
Mobo: ASUS P5Q SE2
CPU: Intel Q8200
GPU: BFG Nvidia GeForce 9400 GT
DDR2: Corsair 4Gb
ATX: CoolMaster 600w
HD0: - WD 320Gb
HD1: - WD 1Tb (500Gb/500Gb)

 

Well, the response is deafening!!

But seriously folks - what it says is that a fix for this is so easy it's just really not worth posting. So, thank you for your inattention: I have probably mixed up my SATA ports.
Cheers All.