I ordered a new, factory-sealed Halo 2 Vista last week from Amazon. Got it yesterday, installed it and everything. I didn't run into problems until I hit the GFWL pop-up after the intro screen.
When I was trying to login to GFWL, it wouldn't let me because it kept saying my product key was INVALID. I was so confused because my Halo 2 game was brand new, factory-sealed. Long story short, yesterday I was on the phone for a total of ~4 hours with 3 different agents from that incompetent CS department. Wasn't able to get a new product key so I just decided to calm down and wait till tomorrow.
Thankfully, 4 times the charm, the guy I spoke to during noon helped me and got me a new product key. Took him a few minutes, but the wait was worth it.
If you're going to buy this game, I highly recommend you do buy a BRAND NEW Halo 2 Vista like I did. Keep in mind though, that if you do run into this hiccup you will have to be very persistent with the GFWL CS so you can play this game under your Xbox Live account.