:hap2: better safe, than sorry
GMail Drive is a Shell Namespace Extension that creates a virtual filesystem around your Google GMail account, allowing you to use GMail as a storage medium.
GMail Drive creates a virtual filesystem on top of your Google GMail account and enables you to save and retrieve files stored on your GMail account directly from inside Windows Explorer. GMail Drive literally adds a new drive to your computer under the My Computer folder, where you can create new folders, copy and drag'n'drop files to.
When you create a new file using GMail Drive, it generates an e-mail and posts it to your account. The e-mail appears in your normal Inbox folder, and the file is attached as an e-mail attachment. GMail Drive periodically checks your mail account (using the GMail search function) to see if new files have arrived and to rebuild the directory structures. But basically GMail Drive acts as any other hard-drive installed on your computer.
You can copy files to and from the GMail Drive folder simply by using drag'n'drop like you're used to with the normal Explorer folders.