Do I need an electrician to install a whole house surge protector?
It partially depends on your competency with electrical work, and what kind of surge protector you get. There are two basic models I know about: 


Square-D makes a module that mounts the same way as a standard QO breaker in the panel: http://surgelogic.com/residential/surgebreaker-secondary-surge-arresters/. It is very easy to hook up, you plug it in just like a breaker, and simply run the one line to ground. (This is a "Type 2" device). There are other companies that make these as well, be sure to get one that can fit in your panel (each company does it differently).
There are also several types of external boxes which go beside the main panel, and hook up to a 220V circuit. These are possibly a bit harder to install (you need to run conduit typically), but may offer better protection and sometimes also have surge protection for phone lines and cable. These come in both Type 1 and Type 2.


If you're comfortable opening the panel and installing a new breaker, then really either of these methods is okay, though the first is definitely easier. 

The "type" I referenced above boils down to (and this is new to me, correct me if I get it wrong):


Type 1 are designed for direct lightning strikes, though you may need a lighting protection system (rod) to take advantage of it. 
Type 2 are designed for indirect lightning strikes. 


Note, having this doesn't mean you don't need surge protection on individual devices. It certainly takes a way a lot of the risk, but it doesn't eliminate it. For expensive items or things that are very sensitive (eg, computer, home entertainment system) it's worthwhile to put a powerbar-style surge protector right at the equipment).