Thanks,
I started with Khalid Mughal's book . I found it pretty good and easy to follow since it is straight to the point. JQPlus is also really good. The toughness of the exam is comparable to JQPlus. But the thing that helps more than anything else is actually trying out many many small programs and observing the behaviour. For "language fundamentals" I found the JLS to be very good and it is available online. I would also recommend Roseanne zhang's site, it is quite good.
The online test by Valentin is much tougher than the exam and can be quite a shock just when you think you have understood the key java comcepts( so don't take it a day before your test
), but I think everyone should take it, since it really makes you think about some fundamental concepts.
I did start off with some programming background, but there is a big difference between writing code before and after preparing for the SCJP in terms of efficiency.
good luck to everyone preparing for the exam.
thanks
Satish