Memory for my Laptop

I always think to upgrade the memory of my laptop because it sometimes pisses me off everytime i download something. Not to mention the performance is really slow and i really hate it. Right now i am checking out at Buy.com and probably buy laptop memory. I have seen plenty of memory from the top of manufacturers like Crucial, Corsair, OCZ, PNY and more. The one that i like offers free shipping and rebate is available too. I think i may go ahead and order it now.