Okay, so for the past 4 days I have tried my best to look for an answer for my question, searched, searched, and searched. As I did find a lot of information, I still would like a more direct answer, so I'm breaking down and just asking. Now I understand that it is better to have paired RAM. I have the Intel iMac 17" with 512 RAM...I will be upgrading sometime in the near future, and I plan it to be my only RAM upgrade. Should I buy a 1 gig stick for a total of 1.5 gigs or just buy another 512 stick with a total of 1 gig and the "performance" of paired sticks? Since I won't be upgrading again after this, is it better to have 1.5 or 1 gig paired? Sorry for another RAM question, thank you...