Android 2.2 - External SD card not working - says "Blank External SD card" -- Why? OS: Android 2.2

Device: Samsung Galaxy S

All of a sudden my external SD card has stopped working.

Error Notification:

&gt; Blank External SD card
&gt;  
&gt;  SD card blank or has unsupported file system.


The last thing I did before this was to record some video, which was set to record to the external card, and then plugged it into USB. 

I also installed USB drivers for the phone from Softpedia as Windows wasn't recognaising it by default. After installation the phone's memory showed up as a removable disk but the external card did not. Then after unplugging the device from the PC I had that error in the notification bar.

How do I recover my SD card? Do I need to format and therefore stand to lose the data on it?
I clicked format on the device, causing the SD card to show up again in Windows.

Format thankfully did not actually format it - in the sense that it didn't wipe the data. I only know this because I have installed the demo of ZAR, which has found image and video files to recover.

My options now are to either buy the full version of ZAR, on the assumption that if it recovered images and video the other data is intact, or to find an alternative program that's free.

Edit: I am currently running PhotoRec, which contrary to its name, has so far found mp3 files and a txt file to recover. I am hoping it's also able to read obscure or non existent file extensions, so that apps which had decided to locate themselves on the SD card can be recovered.