There’s been a lot of discussion about the value and safety of taking a supervised break from your HIV treatments (called a structured treatment interruption). The consensus now is that they may have more risks than benefits, but it's an evolving area of research.
In early 2006 a big international trial called the SMART study, which used CD4 cell counts as a guide to stopping and restarting HIV treatment, was stopped early when it was found that people taking a break from treatment were much more likely to become ill not only because of HIV but due to other serious causes as well. Another treatment interruption study conducted in Africa - an arm of the DART study - was stopped soon after when it was shown that people who took treatment breaks after fixed cycles of treatment were more likely to develop AIDS-defining illnesses.
If you are considering taking a break from your treatment, make sure that you discuss it carefully with your doctor beforehand.