I don't think so. Not without prying open the laptop and creating some kind of clever hardware mod.
I suppose if your other PC's graphics card has S-VIDEO output, then in a complicated setup, you could purchase a USB video capture card with s-video input, hook it up to your laptop, boot the laptop, hook your PC to the video capture card using an S-VIDEO cable, thereby utilizing your laptop as a display for your PC.
But this is not practical because it would require you to power up both your laptop and PC, and graphics performance won't be as good.
My advise, just hook your PC up to an independant display.