I'm pretty much sold on getting the 24" iMac 2.8 GHZ. However, the price to upgrade to 4Gb's is $700+ extra. How is the memory set up in the iMac (2 slots both 2GB each or ?) and how easily is it to install it yourself? Also, if you could point me to a store such as newegg with the appropriate upgrades to max out to 4GB's, I'd appreciate it. Thanks.