Hi Dave,
There are quite a number of different cables svcailable on eBay and I went for one which had the HS-CAN/MS-CAN switch, which allows you to access all of the modules on your Galaxy.
I paid £19.90 but you may well find one cheaper from another seller:
http://pages.ebay.com/link/?nav=item.view&alt=web&id=271959014957&globalID=EBAY-GB if you're handy with a soldering iron, you can buy one of the very cheap ones for around a fiver and rewire the plug yourself (you'll also need to add a mini toggle switch). I can do this type of stuff but life's too short and I decided to just pay the extra money!
FORScan is a really well supported application that's still very much under development, so they're adding features and fixing bugs all the time. The developers are very responsive and will offer help with diagnosing faults and issues (I got a response within 24 hours of posting a request for help).
ELMconfig is totally unsupported and has not been updated for some considerable time. It's still available for download, but can't do a great deal of useful config on the MK3 Galaxy. As as it's free however, it's worth having just for the few features you can play around with (I've set my doors to auto lock and setting your Satnav to display in the Convers+ screen also works well apparently). Many of the features don't work at all though and I believe it was initially developed for a Focus model from a few years back.
To answer
El_Dude's question, both applications work on PC only. FORScan is available for the iPhone and for Android though, but you'll need to pay for these versions.
Hope this helps.
Ebo.