I'm updating Windows 7 to 64-bit, how do I move my Steam games?

Solution 1:

Most, if not all, of the Steam games I have are 32 bit, and the client is only 32-bit, so they're all run with WoW64. If you're going to be reformatting your hard drive, you can back up the game files to avoid redownloading fairly easily.

1. In the Steam client, go to "Steam" >> "Backup and Restore Games..." >> "Backup currently installed games" and select where to store the content.
2. Install Windows/whatever
3. Reinstall Steam client
4. Open the client, go to the same backup/restore dialog, but select "Restore a previous backup", and point it where they were saved.

Solution 2:

Steam only has a 32-bit version, so it's quite easy to transfer between Windows 7 versions. Here's what I did:

1. Copy the Steam folder from C:\Program Files\ to backup.
2. Install Windows, whatever, do your thing
3. Install Steam.
4. Copy the backed up Steam folder to C:\Program Files (x86)\, overwriting what you just installed.

Steam's pretty good at detecting anomalies and fixing them or updating, so I wouldn't be too worried about having conflicts after you copy the folder over. I certainly didn't have any problems.

(By "protect" I assumed you meant you want to keep your downloads, so you don't have to download them again. Steam will let you re-download/re-install your games, of course, so you don't need to de-register them or anything. You might want to de-register games that also use a third-party activation like EA's or Games for Windows Live, if you can, but that's a different question.)