Mining is entirely worth it, but whatever you do, do not buy the mining contracts on eBay - they are so overpriced you would not believe!
My friend actually sells contracts on eBay as he has ~35 or so GPUs, and he makes a fortune off of it because theyre unaware of how little coin they'll make for the cost of the contract!
At this point i'd probably suggest against buying hardware for mining now as the difficulty is rising very quickly so your ROI is getting further and further away (a week ago I'd of said it's worth it).
In terms of investing, I'd read the market before making a move, but imo I think we'll see another big rise pretty soon, but how high it goes and how long it stays there is anybodies guess!
If you can trade already, then there is EASY money to be made. I'll admit I'm pretty bad, but on 2 trades I got 10% profit - if you use the website I showed above (coined.com), you can view the live charts for MtGox etc, and if you trade on BTC-E there's usually a 1-2s delay. So if it goes up on Gox, it will generally follow on BTC-E as well, and the same with when it drops too. There are so many bear traps all the time if you can predict them you can probably make 10% each trap.