I've got an early 2008 iMac with 2GB memory (1+1), and want to upgrade it, as I'm having a few issues running iPhoto and iMovie, plus a few other things, well. My target was 4GB of memory, as 6GB gets a bit expensive for an aging computer. So, my options are: (all are PC6400 DDR2 800MHz) 1) Replace memory with 2GB + 2GB (~$60) 2) Replace memory with one 4GB (~$70) 3) Replace one 1GB memory module with a 4GB module, leaving 4GB +1GB. (~$70) What would be my best choice? In particular, does option #3 have any issues -- would it be better than option #2?