Camera Raw 4.6 page:
<www.adobe.com/support/downloads/detail.jsp?ftpID=4040>
Here's the part you need:
Manual installation Windows
1. Exit Photoshop CS3 and Adobe Bridge.
2. Open My Computer.
3. Double-click Local Disk (C:).
4. Navigate to 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 Step 4.
7. Launch Photoshop CS3 or Adobe Bridge.
There is a separate Camera Raw forum, should you have more questions after installing 4.6.
When you relaunch Photoshop go to Help > About > Camera Raw which should then indicate the newer version of Camera Raw being installed. If it doesn't then you've put it in the wrong place so now start over all over again (without going to jail) and try again. :-)