First off, FU beer you wanker
What type of headset are you using? If it is a USB one, the game has a real hard time picking that up so if you have a 3.5mm jack on it, use that. It wouldn't matter if you put it in the onboard sound or on the sound card it will still work regardless. You just need to tell the computer what it's going to use.
As for the game crashing on start up, try updating the game to 1.3 (should be done automatically if done through Steam) and also make sure that your video drivers are up to date. It could also be crashing because the game cannot render the current settings. To sort this out you need to find your player config file.
If you are using Steam this is: C:\Program Files (x86)\Steam\steamapps\common\Call of Duty 2\28\players
If you are using the disc then it will be C:\Program Files (x86)\Activision\Call of Duty 2\28\players
If you have not yet been able to connect at all then you will not have a player profile to edit. If that's the case I can send you mine and tell you which bits you need to edit. You then need to look for the file config_mp.cfg and you are looking for these lines:
seta com_hunkMegs "256" or something similar. Change that value to 512. That will allocate the game more memory to run some of the more demanding stuff the mod has and the maps that have a lot on them.
seta r_rendererPreference "auto" set that to "dx7" instead of auto. It will force the game to render in DirectX 7 and not be such a dick when you are starting it up. Also make sure you are running the game in compatability mode for Windows XP SP3 and administrator.