zlatan24 - Recovery Toolbox for Outlook is not free, it's $49.95! Ironically, I downloaded and tried this software a couple of days ago because my wife needed to access a backup of her ost file on a non-Exchange computer and I was looking for ways to convert it to pst and open it. Recovery Toolbox for Outlook seems to work, but it only allows you to recover the first five items in an ost when in trial mode. In my wife's case, these five items were contacts, which is not particularly useful...
Two further points: at $49.95 this tool is easily $150 cheaper than its competitors (from my search of a few days ago) and two, a caveat, when you DO convert an ost to pst it seems to automatically insert the contents into your current pst. Thus, when I opened Outlook on my computer after running the tool, the five items from my wife's ost file showed up as new items in my inbox! I suspect that this is something that can be adjusted/controlled in the options when runninng the application, but it really shouldn't be the default behaviour. I would have thought that a pst file would be generated and that the user would be prompted for a save location and that it would then be up to the user to open the resulting pst file from within Outlook, without touching the default pst!
At any rate, I'd be interested if you are aware of a free version. I can't see it on the page you linked to, though...