you dont have to order ibm's ram, you can get whatever (as long as it's the right version of ram). i usually check www.dealram.com
. i ordered more ram from ibm when i ordered my computer because they happened to be cheaper than i could find elsewhere, which was very surprising (though most likely due to the epp discount).
installing the ram is as easy as it can be. unscrew the one screw on the door, line up ram in slot, push it in at the correct angle, and click it in. reinsert door and screw.
it probably took me 30 seconds