I believe you are confusing dual channel and fsb. The cpu is currently running at 15(multiplier)x133(fsb)=1995mhz.
1) Unless you're on a tight budget, it would be much more cost-effective to buy a newer motherboard, cpu, and ram. None of the newer cpu's are made for socket A or 478. You would get much better performance out of newer parts.
If you prefer AMD, look at the Athlon 64 x2's or Phenoms. Or if you want to look into intel, look at the core 2 duos or core 2 quads.
2) Your motherboard may be able to handle a 400mhz fsb, but your current cpu would not.
If you're interested in overclocking, I would look into the newer intel core 2 duo's or core 2 quads, as they overclock excellently.
Hope that helps.