Can I take my dell inspiron laptop to staples to get a memory uprade?

So staples has a PC tuneup where you can bring your computer in and they can upgrade it for a fee. I live really close by a staples and I was wondering if I can take my Dell Inspiron 1545 laptop with a 4gb RAM memory on 64bit operator to staples to have them put in an 8gb RAM memory. I read the booklet that came with my computer and it says "Possible Memory Configuration: 1gb, 2gb,4gb,6gb,8gb" I'm guessing that means I can upgrade my laptop to an 8 gb memory? I need more storage space because my computer is starting to run slow, and I have been researching for hours trying to find out how I can speed it up and everyone says I need more RAM. Is my laptop even able to get that much? I am soo frustrated right now, and i'm just looking for answers. So if anyone can help please please please help! It will be much appreciated!(: also, if I can does anyone know how much it might cost?