Old computer as external monitor?

[lhamil64]

I have an old computer (laptop) that i would like to use as an external monitor for my new laptop. The older laptop i formatted and installed Ubuntu Linux on it (but i have another hard drive for it that has windows 98)
My new laptop is running Windows XP Home Edition.

Is there software (similar to maxivista) that will allow me to do this? I would prefer free software.

Thanks