Checkout using the SharePoint Drafts folder.
Here's what the process is like when you select the Use my local drafts folder check box:
When you check out the file, it will be stored in a folder on your computer. If you're using Microsoft Windows XP, it is checked out to My Documents\My SharePoint Drafts. And in Windows Vista, it's checked out to Documents\SharePoint Drafts. This can be very handy when you use a laptop. You can work with the file as you travel — even if you do not have an Internet connection to the library.
When you edit and save the file, your changes will get saved to your Drafts folder, and not to the library. Furthermore, you'll notice that saving the file will be much faster, because you're not saving it through an Internet connection.
When you check in the file, others will then see your changes. And the file will be available for people to work on.
In short, we recommend selecting the Use my local drafts folder check box. It allows you to travel with the file, and it makes saving the file a lot faster.