If your BIOS is set to AHCI, you need to install the F6 drivers before Windows will see the drive. That said, to use AHCI you need to be sure that your HDD supports Native Command Queueing.
AHCI has a negligable affect on performance (some may argue here, I use it and I haven't seen a huge difference), so it maybe better to switch the setting to Native (which will allow Windows to see it without drivers if you are using the Intel controller) rather than AHCI. This is done in the BIOS, read the manual, it will explain how this is done. Once switched then boot up off your OS CD and you should see your HDD.
If you are determined to use AHCI (and your HDD support Native Command Queueing) then you'll need to put the AHCI/RAID driver onto a floppy. Once this is done, boot off your OS CD and when prompted, hit F6 and install the AHCI driver. After this is done the CD will continue to boot, once complete you should be able to see the drive. Be forewarned that some drives supporting SATA II and NCQ have a jumper that is placed so that by default the drive is seen as SATA I and unable to use NCQ (AHCI). This jumper will have to be removed before you can proceed with an AHCI install.
Thanks for your reply, but I have no floppy drive.
On top of that, I got my entire PC as a set; everything is installed in place.
As I have some data in an old IDE hard disk, I had to put it in myself & installed XP from there.
It was after the completion of the XP installation that I discovered XP couldn't see my new SATA hard disk