I have a macbook 2,1 mid 2007, it has 1 GB memory - can I upgrade to 2 GB memory. I want to install Lion.

You can upgrade it to 4GB.

(66082)

You can install 2x2GB, which is 4GB, however your system will only recognize 3GB. There is a benefit to going with 2x2GB versus a 1GB and a 2GB, as the Intel architecture runs just a little bit quicker with a matched memory pair ... 3% to 5% quicker, if I remember the tests correctly.