CR2 are Canon RAW files.

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Download Adobe Camera Raw Plug-In 4.1.1

To install with Adobe Creative Suite 3 or Photoshop CS3:
1. Exit Photoshop CS3.
2. Open My Computer.
3. Double-click Local Disk (C:).
4. Navigate to: c:\Program Files\Common Files\Adobe\Plug-Ins\CS3\File Formats
5. Move the existing Camera Raw.8bi plug-in to another location (for example, a new folder on your desktop). Ensure you keep this version in case you need to revert back.
6. Copy the Camera Raw plug-in, Camera Raw.8bi, from the download into the same folder as in step 4.
7. Launch Photoshop CS3 or Adobe Bridge.

Note: If generic camera thumbnails appear in Adobe Bridge, follow these steps:

1. Check to make sure the plug-in was installed in the correct directory in step 4 above.
2. Start Bridge.
3. Choose Tools > Cache > Purge Central Cache.

OK. Now, I can open the .CR2 Raw files in Adobe Photoshop CS3.

HTH