If you have a abundance of money to spend then go water cooling if not air. You can probably get a cpu loop going for 250 - 350$ using a rasa kit but if you add gpu in there will cost you a bit more. If you looking for a inexpensive way to do it then air is the way to go. If you want closed water loop can get those starting at 60 - 80$ but your better off with a higher end air cooling then a closed loop water cooling system in my opinion. if you want water cooling custom loop is only way to go!!! because you are using a dell case make sure you have the clearance for a beefy air cooler before you purchase it as well or else you will be running it with the side of your case off at all time. as for the question of is water cooling worth it, it all comes down to how much you want to spend on cooling your parts and if you want to spend the time to put a loop together or if you want to slap something in there quick and be done with it. I enjoy building water cooling systems i would build one just for the enjoyment of doing it ( hobby ) to someone else it might not be worth it. its all personal opinion.