I have the 6 cell and at times have gotten almost 7 hrs, how often do you charge it, they say not to charge it until it gets to around 60%, I sometimes go a couple of days without charging mine with using it about an 1 hour per day, or like the other guy said maybe your battery is just shot.....try to let it totally drain then charge it, I dont think these batteries retain a memory like the older ni-cads used to..try calling Dell Tech Support..that in it self will be a nightmare, if its under warranty demand a new one, otherwise if its not under warranty try ebay...skip Dell all together....Dell tech support is so far the best reason I have seen lately to drink
"oh my gosh be golly I be seeing that your warranty has come to an end..I will be glad to transfer you to our Sales Department where there be someone who will be assisting you today on this matter most quickly"