The Bethblog has posted a blurb about Games for Windows Live, which is basically like Xbox Live I guess.
PC users now get achievements and friends lists similar to how Xbox
Live works. Here some cool things you can do with Games for Windows
1. Earn achievements. You can create a free Games for Windows Live
profile or link your Games for Windows Live profile to your existing
Xbox Live profile. That’s right — you can earn Fallout 3 achievements
twice, for both PC and Xbox 360. To link your Xbox Live profile, create
a Games for Windows Live profile using your Live ID (ie, the email and
login you used to link your Xbox Live profile to Live ID — that is, how
you log onto xbox.com)
2. Once you link your Xbox Live profile, you’ll be able to see both
your Games for Windows Live and Xbox Live friends together via the
Games for Windows Live dash.
In addition, they wrote up a small note about save game issues with Fallout 3:
3. Question: Hey I was playing the game for a while, then logged onto my profile and my saves are gone? What happened?
Answer: Your saves are kept in specific directories tied to your
profile. But don’t worry - you can go into your My Games folder and
copy those saves over to your Profile’s save game directory.
For example, on my computer running Windows XP, under the Saves
directory, I have two folders - Player1 and acheng. I can simply copy
all the saves from Player1 to acheng, and I’m able to access them while
logged on with my gamertag. On Windows XP, look in your My Documents\My
Games\Fallout 3\Save folder. On Windows Vista, the path is
For more troubleshooting tips, visit the Games for Windows Live technical support pages.
I didn't know much about this Games for Windows Live thing until I read this. Looks like you're able to play some multiplayer games crossplatform with the 360 (which means they probably nerf PC users to compensate for the inaccuracy of console controllers).