I've read this solution once on MandrakeForum. I did not try, so make sure you know what you're doing:
1- Take the hard drive from your laptop,
2- Remove the hard drives from your PC, and put the laptop's hard drive instead.
3- Install Linux on the PC with the laptop in mind: select the packages to make sure that all packages needed by your laptop's hardware is installed (eg: PCMCIA); also: choose a console boot, not a graphical boot (technically speaking, boot in runlevel 3).
4- Put back the hard drives in their proper places.
5- Boot the laptop, login as root, and reconfigure your X server.
6- Start X (startx) and use Mandrake Control Center to make sure all other hardware is well configured.
7- If all is well up to this point, you can put your laptop in graphical boot mode (technically speaking: runlevel 5 at boot).
Good luck. If you don't feel this is the solution for you, go and check what is available here:
http://old.lwn.net/Distributions/
Yves.