You can easily back up your bookmarks and more by syncing them to your Google account. To set up sync, go to Wrench > Options > Personal Stuff > Set up sync. To access your bookmarks on another computer, enable Google Chrome sync on that computer. You can learn more about sync in the article in my references.
As 3xl4x mentioned, you can also export your bookmarks by going to Wrench > Bookmark manager > Organize > Export bookmarks. You can import the resulting html into Chrome and other browsers when necessary.