Plus.. you can always carry them forward to any other machine you decide to upgrade to later on.
		
		
	 
 
+1
 
it is not like bying a new radio for the car or mag wheels, it is a re-usable part.
 
OP, depends on what you do with the computer, the SSD will help with day to day making the system feel a lot snappier. You only need a 60-12GB drive as the existing raptor will do fine as a programs / games drive (for the ones you do not install on the SSD).
 
upgrading the ram to 8GB is possible, but limited benifit unless needing more ram (otherwise windows is generally good at caching files in excess RAM). The GPU could do with a upgrade if you are a gamer, but the 23" monitor proberly is not showing signs of needed a super fast GPU. 
 
Getting a good after market cooler and doing a little overclocking can help in some things as well ,but then most games released recently are generally console ported, so even 5 year old hardware still runs them acceptably.
 
All told though, that would be a bit over $500ish for most of the above changes. Of course, best to improve in areas you are likly to get the best benift from.