Normally the answer is yes. But not all memory or motherboards are created
equally so you may or may not be able to combine these two.
Usually the computer would realize that the speeds are different and run at the
slower speed. Some computers will also slow down the memory FSB speed if it
senses too much memory to run at the higher speed (for example 1 DDR400 stick
will run at 200MHz FSB while installing a second stick of DDR400 memory will
reduce the speed to 166MHZ and installing a third stick of DDR400 will reduce
the speed to 133MHZ).
Paul
