I have a Sony Vaio desktop pc purchased around 3 years ago, it originally came with 512MB memory installed, but I wanted more, just so I can have my 10 shopping comparison windows and watch a movie while they refresh automatically.
I did a lot of thorough research, went to every memory selling merchant via Google and had their site scan my system each time to give me a recommendation of which memory is perfect for me. (Crucial's website was the MOST helpful, their scanner tells you how much you have, which slot has which, which volts and pins will work best, AND they give you over 4+ memory upgrade products) - However, this same memory on their website was over $60.. until the lifesaver Amazon!
I have installed it, and it was detected the first reboot and the pc now has 1GB memory ...I dont know how to exaggerate this speed change!! its like watching 10+ dvd movies at once without freezing up!! ITS THAT FAST!
I love it. My research found that while Kingston may give you cheaper prices, Crucial gives you a much better performance - overclocking!