when I was studying for the A+ exams I used a lot of different materials including
M Myers A+ passport
A+ in depth (Jean Anderws PhD)
E Leaning Center CBT
About a dozen practice tests from all over the place
now heres the moral of the story:
the A+ tests are REALLY easy so you dont need all that stuff, I studied for about 2 months for the hardware test using all the above and got 96% and thought the exam was easy so I spent 4 days cramming for the OS test (just using the E Learning Center CBT) and that was all the study I did and I got 92% on the test.
Now, Microsoft tests are somewhat harder and i'd recommend a minimum of 4 weeks hard study with 2 sources e.g. CBT and Book for each test and pleant of practice questions.