hi there, hopefully someone can help ? i,m about to upgrade the memory on my imac and i was wondering if i need to remove the memory that,s allready installed and simply swap it over or do i leave it in and add to it ? i have an imac 2.4ghz intel core2 duo with 2gb of 667mhz ddr2 sdram. i,ve ordered a 4gb kit (2 x 2gb) thanx for any help you can give ! happy xmas