Microsoft has one of the best cloud storage solutions on the web. Skydrive which is free allows for over 25gb of file storage. Skydrive also has the ability to create Microsoft documents such as Word, Excel, PowerPoint and OneNote on the fly.
If you want an easy way to navigate your Skydive using Windows Explorer, then SDExplorer is an excellent option. SDExplorer has an Advanced Edition as well as a free Edition. SDExplorer requires you to login using your Skydrive credentials and maps to your drive in the cloud. See a list of the Free vs. Advanced Editions here.