<p>I changed the folder that my WordPress installation was in.</p>

<p>However, this worked fine, except now all my images are not showing up.</p>

<p>The problem is that each post has the full url of the image in it. (not my doing, this seems to be the default setting)</p>

<p>Is there a tool or a quick fix available for this?</p>

You need to update your settings to reflect the directory change on the settings page in your admin section.
Edit:
Since it seems to be a problem in the posts themselves, you'll probably have to write a quick fixme script that runs through your post table searches for
```
'="/'
```
or something similar and updates any hardcoded links.