PThread vs boost::thread?

I'll go in the opposite direction of everyone else - learn (or at least familiarize yourself with what is available in) pthreads.

Since boost is mainly just a wrapper around pthreads (on posix platforms) it helps to know what is going on underneath. In attempting to be generic, boost leaves the platform specific functionality unwrapped. In order to get to it you need to use the native_handle() calls. In order to use the native_handle() calls you need to know what the platform offers.

Think of it like sockets. There are dozens of socket classes and frameworks. But ultimately they wrap the underlying platform's socket API. Your understanding is always richer by knowing it - and knowing in what ways your class abstractions might have short comings.

Go for boost::thread. It's closely related to the work on the upcoming C++ standard threads, and the interface is quite easy to use and idiomatic to C++ (RAII instead of manual resource management).

boost::thread is a very nice and portable abstraction. I would certainly use it, but also learn the native thread api, like pthreads, so that you know how threading works on your platform.