Another follow up to Manoli's post is that on your initial computer you should make sure you display parent folders in LR's Folders panel. For a simple example, the Folders panel may show folders such as 20121225, 20121226, 20121231 but does not list their parent folder "My Photos". So when you take the catalogue to the other machine all three folders would be missing and you'd have to go through "Find Missing Folder" three times.
By contrast, if on the first computer you right clicked 20121225 and chose "Show Parent Folder", on other computer My Photos would still show as missing but would need "Find Missing Folder" to be run once, and its subfolders would be fixed automatically. The more folders you have, the more time you'll save if you make sure their parents are displayed in Folders panel.
Not sure if I explained that clearly!
John