Any IDE to CF adapter should work fine. I personally would stick with a conventional HDD though. CF cards a silent and in older systems faster, but most CF cards can only transfer at 30MB/s, whereas the final IDE version has a 133MB/s speed and most of the recent IDE HDDs support that and can maintain 66MB/s+ so are a lot faster than a CF card. Also as this is going to be a PC it will probably be running Windows? Windows needs a HDD cache and this will keep writing to the HD, and with a CF card it does have a finite number of write operations, so this could end up being an issue. Also if you are considering Windows 7 then a 100GB+ system partition is recommended, although you could probably get away with 50GB for a while. With XP you can live with 10-20GB for some time.

You can also buy cheap 2.5" IDE or SATA laptop HDDs for around £35 these days so now expensive.

How will you be altering the ports on the back of the case? I've seen most people cut a large single hole and then use a sheet of metal to make a backplate for the actual ports. With a Laptop motherboard you might be able to reuse the existing backplate from the laptop shield.

The other issue is display. How will you be running the display? Normally laptop GPUs output their main display to the internal LCD via a ribbon cable, with many having a second output via a VGA or HDMI port. However these extra outputs normally need setting in the bios and software before they will becoming active and work as the default output, so remember to check this before you dismantle the laptop.
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