This vQmod uses the excellent code snippet provided by billynoah on the Opencart Forums here: http://forum.opencart.com/viewtopic.php ... 36#p459336
Made this into a vQmod for those of us who prefer not to alter core files unless absolutely necessary but all props should go to billynoah on this one

To install simply upload the vqmod folder to the root of your Opencart install (where you can see admin, catalog, system etc) or copy the xml directly into the vqmod/xml folder.
Works on OC1.5.6 and OC1.5.5.1
No files are overwritten and to uninstall simply delete the xml file.
Download page
Tested on the default theme and working fine, if your custom theme doesn't mess with the code too much on the product pages then this may work for you too - try it and tell us!

Please report problems/bugs to stokeyblokey125@hotmail.com