Keeping the old hard drive!

I've installed a new motherboard and cpu (and other bits) but would like to keep my hard drive. I couldn't initially get the bios to recognize my sata HD so I disconnected it and reinstalled windows XP on a spare IDE HD, reattached the sata, fiddled a bit and Bob's your auntie, it all works.
Now my SATA drive is D: and the IDE drive C: and it boots off drive C: I'd like to keep the SATA as my only HD as it has all my programs including win XP on it but don't know what to do to set that up.
So I guess my question is, how do I work an old HD into a new system?

My guess is the problem is that the Win XP installed on the SATA drive did not have the right drivers for the new mobo and could not access the SATA drive. For this situation you are supposed to be able to fix with a Repair Install. This process inventories all the devices in the system, compares that to the drivers installed on your drive as part of XP, then deletes the unnecessary ones and installs the new ones required. It is NOT a complete new Install, and it does NOT change your applications and data already on the disk. Of course, there are no such things as absolute guarantees, so a full backup of your SATA drive is strongly advised before proceeding.

To do this you need the original Windows Install disk used to get XP onto the SATA drive in the first place. Shut down, disconnect the IDE drive and ensure the SATA drive is connected to the port you want - often SATA_0. Place the Windows Install disk in your optical drive. Boot into the BIOS Setup screens and set the Boot Sequence to your CD-ROM or DVD drive as first choice, then the SATA drive next. Save and finish booting. It will boot from the Install CD and very early ask for some choices from you. Choose to do a REPAIR INSTALL, not a Full Install. When it's done you'll have to reboot, probably with the Install CD removed so it boots from the SATA drive. If that all works you can decide whether to remove the old IDE drive completely or to destroy all its data and re-use it as a data-only device. To use it that way, reconnect to the system and ensure in the BIOS that it is there but NOT anywhere in the boot sequence. Save and finish the boot into windows. If there is any recent stuff on the IDE drive you want to keep, copy it somewhere safe, maybe your SATA drive. Finally use Windows' Disk Manager to Delete from the old IDE drive all its Partitions, then Create a new Primary Partition that is NOT bootable and format that Partition using the NTFS File System. Reboot so Windows gets this all straight in its Registry.