Make sure it has good cooling. I run SETI on my laptops at work, a Dell Lattitude 1Ghz PC, Dell Lattitude PIII750Mhz, and several IBM Thinkpad 390X, as well as having run it on a IBM T23 laptop. They do run a bit hot, but still well within specs, and all run it well.
I don't run it while on battery power, as it drains the battery quickly, but other than that, not a problem. If you have a tualitin core cpu (-M) lappie, those will run very fast times, and also don't run as hot as the others do either.
No experience with AMD powered laptops.