This has been discussed on the Hardware and Software several times. Yes, you can copy - clone is a better term - your OS from your current HD, but the results may vary. A clean install is always clean...
AFAIK it will load your game faster, but the gameplay itself will not improve that much. If you suck, you suck. If you're good, you'll be good with a P4@2.4GHz + Radeon 9800, flying with a mouse.
That means, your ping time is dependent on your net connections, your framerate on your video card and your suckage on your level of skills.