Definitely worth OC'ing mate, i just got rid of my i7-930 which ran 4.2ghz all day everyday would go a heck of a lot higher but it wasn't really needed to just play games.
I have OC'd every chip i ever had and all of them are still alive and kicking in friends computers still to this day including my q6600 which ran 24/7 4.0ghz ( was one killer chip for OC'ing in its day )
I've never had one die on me yet (touch wood) just dont go over 1.4 volts on the vcore if your not confident and watch your temps.
The I7 i just got rid of was running 4.2ghz 24/7 water and is now in my friends pc running 3.4ghz on air ( i could push it further for him but he is not technically minded so it was a safe oc for him )
My new i7-3820 will bench 5.2ghz but i just run 4.4ghz as its all i need
I am using water cooling but even on air you can get some massive performance gains for very little cost.
Just do your research with coolers as cost doesn't always equal better there are some really killer coolers for under the $40 mark around.
If you go down this road and want help getting a good cooler setup going just sing out.
But if you dont want to spend $1000+ on cpus and i know that exact feeling you can get free upgrades with this "black art" its not really hard just nerve wracking on your first time. But just research research and when you sick of reading about ocing I7's read some more