Yo people, If your having the good ol' Steam Message of:
"Steam Servers are currently too busy to handle your request. Please try again in a few minutes"
I had the same problem but I managed to fix it. This might work for you.
When you put the disk into your PC, did it just go onto steam and try to get you to download it? When you clicked download, it comes up with the above message. If it didnt ask you for a Product CD Key, then follow these steps:
1. Calm down, there is NO point in going on a killing spree to Steam HQ. Trust me, they arent worth the bullets.
2. Delete Steam Folder. Find the Steam folder, and delete its whole contents.
3. Go onto Steam.com and download the installation file.
4. Run the Installation application. It will probably go onto an Uninstall program. Let it unistall, then re-run the application to install Steam.
5. On Steam, make a new account and verify it.
6. Put your Empire Total War disk into your PC and run the disk.
7. From here on it should go onto the screen with "Install Empire Total War" and ask for your CD Key (found on the back of the manual with the game).
8. Type in your CD Key, click OK, and let it go into Steam.
9. In Steam, it should now begin installation perfectly.
10. Once its finished installing, you can run the game from the Steam Games browser.
11. Sit back, and Enjoy.