I've managed to find a bit more information about Pixelmator, which I thought I'd post up here in case anyone else is interested: http://www.ronmartblog.com/2012/05/ask- ... about.html
. It's only for Mac users though, which is a shame as its reasonably priced for something to get you started. Available from the App Store.
Ron's overview video is not the most exciting, but you get the point...if you stay awake
Pixelmator's not great for RAW files, as I've found out here, but for anyone starting out and wanting to try some editing, it's a good inexpensive option, so I'll stick with this for now until my skills improve (ever hopeful) to make it worth splashing out on Photoshop or something similar.