If your computer is running slowly, odds are good that it could use more memory. Many times if you are experiencing programs taking a long time to load or frequent crashes, a memory replacement or upgrade will get your computer back to running smoothly. Memory is available for all brands of computers including Dell, Lenovo, IBM, Hewlett Packard HPs, Mac / Macintosh, Acer, Compaq and many more. Often used memory is just as good as new, and can be purchased for far less. Care should be taken with inexpensive memory however, to purchase a good brand. Many companies such as Crucial, PNY, Samsung, Hynix, and Patriot are reputable and reliable brands of memory. Older computers often don't need much in the way of upgrades besides adding new memory, also known as RAM. These computers could run programs fine a few years ago, but newer applications and operating systems are more demanding, thus the need for more memory. This is especially true for operating systems like Vista, XP, Windows 7, Tiger, Leopard, and the latest Snow Leopard.