You can also use these sites to store often-used files. You'll have access to them anywhere you have an Internet connection. Keep personal files password protected. You can share files with friends. Or drop them in a public folder for the world to see.
SkyDrive is from Microsoft's Windows Live. Think of it as an extra hard drive on the Web. And what does it cost? Zip. You have to sign up or log in with your Windows Live ID. You can store up 25GB of data.
Cost: Free
Link: skydrive.live.com
System: Windows XP, Vista and 7, Mac OS X