I just upgraded memory in my Pavillion ZV6233NR to 2 GB last week. The memory does not have to be equal in both slots. You can just upgrade the easily accessible one, though I recommend upgrading to the max (2GB) as old memory is only going to get more expensive as time goes by and later on you may not even be able to find it. I used 1 GB PC2700 200 pin Patriot SODIMM in each of the slots. The one under the keyboard is not hard to access. Download the service manual for your laptop from HP website. It tells you how to access it. There's also a video on youtube (I don't have the link anymore).