How do I determine what kind of RAM I need?

I just got a Sony Vaio and on the box it says it has 1 GB (512MBx2) DDR2-667 SDRAM expandable to 2 GB.

I want to expand to 2 GB but I don't know much about this, someone said something about making the pin numbers match or something weird like that...

 

basically any ddr2-667 RAM will work. does it have 4 memory slots or 2? you may need to replace it all for 2 gigs or you might be able to just add another 2x512

 

Hmm, I'm really not sure, I have no idea where the RAM is even stored, ha ha. Pretty pathetic considering I work in computers, but I mostly do programming and don't even open them up often.

It says 512x2 expandable to 2 GB so I'd assume that means 4 slots of 512? Or is that a bad assumption to make? I can't check for sure until I get home.

 

when you get the chance, run this: http://crucial.com/systemscanner/index.aspx

it will tell you what you need. you dont need to buy from them though, newegg is your best bet.