Possible Duplicate:
Can I use my laptop as a second monitor for my desk computer?
The laptop works fine but is slow. The desktop works fine doesn't have a monitor.
Possible Duplicate:
Can I use my laptop as a second monitor for my desk computer?
The laptop works fine but is slow. The desktop works fine doesn't have a monitor.
Really you need to fix up one of the systems to be the good one ;) Anyway, yes, like other have said you'll need a video input on the laptop, another way would be to network the machines and use VNC, run your hard-core resource hungry apps on the desktop whilst viewing them on the laptop, but this requires a high speed network between the two or you'll suffer a lot of lag.
You're laptop likely has no video input port, so you cant pipe the desktop output to it. You might be able to run 2d apps over vnc from the desktop, but i wouldn't expect much from it.