I'd get the Dell unit next. There can be issues such as an old battery taxing the power supply but the signs are usually very clear when the battery life is over. Tell the forum how many minutes you get on that old battery.
I have a Dell inspiron 1545, the original charger adaptor (box on the cord) quit working about two months ago, the blue LED indicator would come on and it would charge half of the time you wanted it to. Also (sounds odd) but it would work in different outlets in the house and not others. So I ordered a replacement (exact same thing, all specs identical). It worked for a month (till it was out of warranty) now neither will work at all.
Can there be a problem with the laptop that is causing the charger to go bad? did I just get a bad streak of luck and a bad new charger? odviously when the LED is on it will work, but is there a way to test the box other than that?
I use my laptop for school work because it is much more convienent than my PC , so any help I could get would be great, thanks kurt