Personally, I've found in the past that it's probably helpful to know more than just 'some' from CBTs. But, setting that aside... if I just going for my initial SCJP now, I'd probably be targeting the 5.0 exam. Best, imho, to go after the most up-to-date standard and be aware of how it works.
But then again, I'm kind of biased as I'm also the person in my company who drove the move from 1.4 to 5.0 as the version of the language we're targeting.
Theodore Jonathan Casser
SCJP/SCSNI/SCBCD/SCWCD/SCDJWS/SCMAD/SCEA/MCTS/MCPD... and so many more letters than you can shake a stick at!