Thank goodness for warranties. Without my warranty on my Inspiron 1505E laptop, I might be out of luck when it came to power. Not only are the batteries pretty bad, but the AC power adapter I got with mine was also not durable.
Normal usage took it's toll on my power adapter, causing the plastic coating to tear after only a few months of use (about 8 I'd estimate). The wires were exposed (a pretty dangerous thing) and it only got worse as the months went on. The wires began to fray and the power was becoming less and less reliable as time went on.
It's unfortunate that there does not seem to be many alternatives for power sources on these Dell Inspiron laptops, because these adapters seem pretty average. The are great as a power adapter when they work; a green light indicates that the pack is working and is not overheating (else the light will be yellow). However, they don't seem to stand up to chronic, but normal, use very well.
Definitely a necessity for when your battery starts to give out on you, but use it sparingly and carefully if possible.