Wow, thanks guys for all of your answers. I've still got some thinking to do over which lens to choose now lol.
A friend of mine helped me stay calm and enjoy what I have, not being obsessed about the future (I am not saying you are).
I guess I'm looking ahead a bit and thinking that if they make FF sensor cameras more affordable to the general consumer market, then a lot of people might be wanting to sell their gear and it will be hard to sell mine if I want to. I've certainly taken on board all of the comments here though and I feel more comfortable considering EF-S lenses now. I agree that it would be bizarre for companies like Canon to dump an entire technology that quickly, so I guess if in a few years time if my Rebel self distructs from my snap-happy-snapping, there should be (hopefully) a range of crop cameras still available. It would be lovely to think that photography is like the old days where you can put some decent money in your gear and it will last you a lifetime.... maybe with the speed of technology's progress, this is unrealistic, but it's a nice thought!