Of course, I understand they aren't the same, or interchangeable.
But this is my motherboard:
And memory slots:
2 x 184-pin DDR DIMM socket support up to 2 GB
2 x 240-pin DDR2 DIMM socket support up to 2 GB
With 2 DDR, and 2 DDR2, is it possible to use all four at once, or would I have to take out the current two to upgrade?