Don't mean to but in, but I will anyway..
There is no such thing as "new" "oem xbox 360 parts", the only way there would be "new" "oem xbox 360 parts" is if Microsoft Repair Centers we're selling them to people to resell or use for repairs.
Do you really think MS will want to help other people make money on repairing their consoles? I thought not....
Everything is pulled from (hopefully) working systems, however I do believe lasers are new, but not oem, probably as well as a handful of other replacement parts.
The GPU is not a universal chip, its owned by Microsoft and only Microsoft will be able to provide new GPU's, so unless you're buying from them directly (which you're not), its not new.