I have just had exactly the same problem with my rear shocks. Very very easy to change them. Personally i have just got the 35mm suspension kit which will do absolutely fine, i'm still waiting for it to arrive, obviously you can have how ever much of a drop you want, 35mm, 40mm, 60mm etc.. They are gas shocks with uprated matching springs. If you have the money its worth investing in coil overs, which are usually fully adjustable but the normal kits are perfectly adequate if all you are after is a set drop.
The more you drop, the harder the ride will be though. A rock hard ride is rather uncomfortable and doesn't do much for the structure of the car. 35mm drop will tighten it all up a bit but isn't bone rattling. If you start to go below 40mm it starts getting a bit painfull, but saying that if your careful with bumps its worth it for the looks and certainly does improve the handling.
HTH
