I assume you are talking about COD: MODERN WARFARE 2 ruxtmp, MODERN WARFARE 1 worked without any problems in DEDICATED SERVERS.
They screw the multiplayer version of MW2 on the PC to CONTROL the game monetary income. MW1 has tons of free mods and maps running on free dedicated servers, they saw that (ACTIVISION, aspiring new evil empire). So they could release MAP PACKS at $15 each.
So instead the having a good PC with a great bandwidth connection, they made some random user PC the host-server (the one that SEEMED to react better at that moment). I loved MW1, preorder MW2, big mistake, got carried away with the hype, nevermore. Luckyly some months later BAD COMPANY 2 got released, with dedicated servers (not free, you have to paid for them a monthly fee and you cant make maps or mods for it, they are in a great SERVER PC you administer remotely) and I still play it from time to time, best team multiplayer experienced ever. They still could control the MAP PACKS and NEW MODS, and charge for them, so is still not as good as totally FREE DEDICATED SERVERS Software.
But at least they didnt lie to your face like the people behind MW2 saying that the "new" multiplayer connection method was the best thing since free porn on the internet
Back on topic, we dont know how the servers will be run, if the players can connect to each others and play a little mission (lets say 8 people) it will be fine, but to have a big mission map and more than 60+ persons playing, you will need a good PC running a dedicated server with a great internet connection. Like it is done now with IL-2.
We only can wait and see