What do you mean by "run off the desktops power??"
Run off the desktop's power supply or use the desktop's processing resources?
If you want the latter, you'd need to configure the laptop to run as a thin client, and the desktop to be the host server. I have no clue how you'd go upon doing that. :-))
As for electical power, then no way.
My Super P3:
Pentium III-S 1.4GHz @ 1.58GHz, 512K L2
X800XT All-in-wonder, overclocked to 580/600.
250GB HD
2 gigs of PC2100 RAM
QDI Advance 12 mobo, this baby rocks!
SB Audigy 2