My original Compaq Presario R3000 laptop battery had been slowly dying for years, and just a few months ago, it was completely dead. It couldn't even hold enough charge to start up the laptop. Although I can run the laptop purely from the supplied AC adapter, not having a working laptop battery was a genuine inconvenience for me. When the AC adapter plug slipped out of its jack, which frequently happens whenever I'm working on my lap and shifting my legs around, my laptop would shut down immediately without the battery and I would lose all of my work.
I usually head to www.pricewatch.com whenever I'm looking for new computer parts because if I can't find what I'm looking for there at a reasonable price, then it probably doesn't exist. And I couldn't put just any old Li-ion laptop battery into my Compaq Presario. I specifically needed a battery that was designed to fit with my particular laptop model number, the R3000 series. The 4.4Ah refers to how long this battery would last in hours if I wasn't running any computer programs that were using up any battery juice. In working practicality, a 4.4Ah battery lasts me about 2.5 to 3 hours before I need to recharge it, and that's plenty of time for my own needs.
I found the best price for a new Li-ion laptop battery for my Compaq at TitanNotebooks.com. Although this is a generic brand name replacement battery, it comes with a 30-day money back guarantee and a one-year warranty, so I didn't hesitate to order it at that price. My laptop battery arrived within a week, and I haven't had any problems with it in the few months so far that I've been using it.