|The optimal RAM speed is determined by the FSB speed of the CPU (which we don't know).|
"My old HP has 1.36 gig of ram"
That could mean you have 1.5GB RAM with 0.14GB (odd amount) being used by onboard graphics.
"I was given 4x256mb of ram at 400mhz"
Regardless of the speed, I'd say 1.5GB trumps 1.0GB.
And I'm laughing at Skip. Hey Skip, was your comment a vague reference to THIS?