OK everyone,
I called IBM tech support and asked about the 3 models listed above. Here's what he told me: All will have 2mg, the difference is oem, whether it has a cable included or not, along with an instruction booklet, jumpers, hardware, etc.
07N5216 - OEM made specifically for Gateway. He suggested we stay away from that model because you will have a hard time getting either them or Gateway to honor it.
07n5640 - (One I ended up getting) this is oem, but standard. has no cables or hardware but they will send you the screws if you need them. Has a 3 year warranty. No booklet. Does have jumpers. No cable!! CRAP!
07n4775 - Retail version, comes with everything including a cable. Same warranty applies.
The original one I ordered I didn't ask about, (thought it was one of the 3 I was asking about), so I'm not sure what that one is at least we know it has the 2mg, but cables - I don't know.
Any one who has one, let us know (07n3931).
Thanks
TGirl