I'm taking my Java cert 1.5 on Oct 9th...!! Before paying for the exam, I did have a conflict about the version of the exam that I wanted to take. I think 1.6 doesn't have as many resources as 1.5 does and I did not want to take a risk, and that's what made me go for 1.5 instead of 1.6!!
And if I'm not wrong the difference between 1.6 and 1.5 is not that much when compared to 1.5 and 1.4! Not many applications being developed have been switched to 1.6 either! I'm not sure about the last two statements...that's just something that I perceived, but please do correct me if I'm wrong!
The source you mentioned is not a good source for mock exams. In fact, it is a website that contains illegally copied questions from the real exam. Using those questions means that you're engaging in an illegal activity, and it also means you are cheating the exam - you're only learning the questions and answers by heart, and your SCJP will not prove you know anything about Java if you do that.
Please do not use that source. There are plenty of legitimate mock exams available, see the list in the SCJP FAQ.
No problem, I know that not everyone is aware of the fact that some websites contain illegally copied questions. We don't allow posting about such websites on Java, because we don't want to encourage people to cheat and it could even bring JavaRanch into legal trouble.