can i insert a ddr2 1gb memory and a ddr3 memory 1gb at the same time on my board: my board supports ddr3.
It is almost
unheard of to have a board that can support both
memory configurations. The vast majority of motherboards are designed to support one or the other.
That said, it is entirely
dependent on the make and model of the motherboard!
your motherboard? If you post the make and model, we can answer your question. (It's best to include information like that in your original question, then people won't have to ask you, which then means it's take so much more time for you to get an answer.