have older dell 6000 notebook. winxp. online scan says it should have pc2-5300 or pc2-6400 ram. it had (1) 512mb pc2-3200 in it. was slow. put in a 2nd stick of pc2-5300 @512mb. ran better. today i pulled the 3200 stick and put in a 1gb 5300 stick. so i have 1.5gb now. if i had access to 2 sticks of 1gb 6400 stuff i might try it but its old stuff and i dont really know anyone who has any laying around.