It's the overhead on the device that counts more. If the OS runs a bunch of stuff from the get go, and in the background, you will still poke along.
That said, that difference in RAM should for all practical purposes be inconsequential. How each rig behaves will still vary due to other factors. Do the two processors share the same clock speed? What difference is their in screen size/resolution?
I am comparing the HTC Surround and Samsung Focus.The HTC has 448MB RAM and the Samsung has 512MB RAM.Will the Samsung be that much quicker???