I'm adding a note here and on the forums as well here http://forums.steampowered.com/forums/forumdisplay.php?f=812
since I don't know what most people use, Valve really need to sort the mess of Communitys and Forums where the same questions are asked?
Anyway I now have DiRT 3 connecting to GFWL on a Windows 8 Pro x64 PC.
First of all a couple of things to note:
1. I have two PCs here running my Steam acccount and with DiRT 3 installed. A Windows 8 Pro x86 install and an X64. Both have been upgrade installs from Vista x86 and Windows 7 x64.
2. DiRT 3 was working fine it seemed on the Windows 8 x86 PC but the Windows 8 x64 was causing endless problems. I went through endless forum posts but nothing worked. I was some how logged into GFWL in DiRT 3 but not online so any online elements like singleplayer time trial, online multiplayer or downloading of DLC wasn't working. No problems on the x86 version though.
3. There is a list of things which are it appears not issues and I suggest you do not waste your time trying:
3a. Uninstallng both “Microsoft Games for Windows - LIVE Redistributable” AND “Microsoft Games for Windows Marketplace” did not help me.
3b. Reinstalling the uninstalled Games for Windows Marketplace client from http://www.xbox.com/en-US/LIVE/PC/DownloadClient
did not help unless I completely reinstalled or reset Windows 8.
3c. Installing any Windows Live Sign-in assistant or Windows Live Essentials did not help. There appear to be several versions of these.
3d. It's not an issue with you Live Account not being added to Windows 8. I have a local account only and no problems.
3e. It's not a firewall or port forwarding issue.
3f. It's not an issue with the GFWL service being down so ignore any XBox Live related forum posts you come across.
4. If like me you've been driven insane with GFWL on Windows 8 here is what I suggest you do.
4a. Backup your Dirt 3 saved games and settings folder in C:\Users\<username>\Documents\My Games\DiRT3
4b. If you can reinstall Windows 8. Yes reinstall the OS from scratch wiping everything.
NOTE: Windows 8 includes a PC reset option so try that first.
If you didn't save a copy of the installation files when you purchased an upgrade copy try redownloading it from here http://windows.microsoft.com/en-US/windows-8/upgrade-product-key-only
or look for a link in your upgrade copy purchase confirmation e-mails.
4c. Once Windows 8 Pro has been reinstalled or reset download the GFWL client from http://www.xbox.com/en-US/LIVE/PC/DownloadClient
4d. IMPORTANT: Right click the GFWL client iinstaller, go to properties and change its compatibility to “Windows 7”. Save and exit. And then right click the installer, and choose “Run as administrator”
4e. Once installed look for the GFWL client here C:\Program Files (x86)\Microsoft Games for Windows - LIVE\Client (that is the x64 path) and Right click the app executable go to properties and change its compatibility to “Windows 7”. Note you will see two versions, the app and the client, I set the compatibility for both. Run the app and login with your Live Acccount and make sure that you can see for example any DLC you've already downloaded in the past.
4f. Reinstall Steam and reinstall DiRT 3. When reinstalling DiRT 3 or starting it for the first time watch it carefully and look for any installation errors and where behind the Dirt 3 app there is a dialogue box asking to allow DiRT 3 to connect to the internet which you need to allow. If you miss that you'll probably have issues.
4g. Once DiRT 3 has been installed run the game and let it install any components. The GFWL client should launch and offer sign in to existing account, then add your CD key and download your profile which in my case it did.
4h. Once your profile has been downloaded you'll get the option in the game of creating a new one. Quit the DiRT 3 app and replace from backup C:\Users\Admin\Documents\My Games\DiRT3 to.
4i. Run DiRT 3 again and you should hopefully see your saved games and be able to access any online elements.
4j. Use the GFWL client to redownload any free or purchased DLC since doing it from the GFWL client offered in-game will drive you mad