I am a PC user that is seriously thinking of switching to a Mac. I have played with the new iMac Core Duo a few times and I really liked it. I am wondering where is the best place to buy. Online or Apple store? I have heard of some issues with DOA units, dead pixels, and video tearing. Would it be easier to deal with any issues if I purchased from the store. I am planning on upgrading the ram to 1GB and the vram to 256MB.