How long will a laptop battery hold it's charge?
Really depends on the laptop, I have a Macbook Pro and its great for holding power!! However, I used to have a HP Compaq that had a very short battery life. Check out the facts when your purchasing your laptop, because it should state how long the battery life is.
It also depends on the cell type of the laptops actual battery. Some laptops have a 3 cell battery which means you will get at least 3 hrs play time. Keep in mind the battery will eventually die. The best way to keep the longevity of your battery well is to power save. Make sure you let your battery COMPLETELY die before charging it up. Also make sure to let it get a full charge. Laptops with a good battery generally charge in like 1 1/2 hrs. Also if you dim your back light and put your laptop into eco-mode it should also help with the life of the battery. If you want to plug your laptop in and are too paranoid with letting it get low just take the battery off. You can still keep your laptop completely functional without the battery just keep it plugged in to it's power source. If you want to move just pop your battery in real quick move then take it out.