It's one of the best perks of the new economy: free online storage space for your digital files. But can you really trust your data to a free online service? And does it work the way you do? Ziff Davis Smart Business Labs usability tested the three top online storage services to see which one makes you most productive.

Name	Xdrive Winner!	I-drive.com	Driveway
Selling Point	Puts a virtual drive letter on any Windows desktop, bypassing the browser. Available via Palm VII or WAP phone. The first 25MB is free, and you can buy 1GB for $19.95 per month.	"Sideloading" feature lets you deposit files directly to your I-drive account without actually downloading them. Photo album features are especially strong. Tops out at 50MB of storage.	Me-too features. Gives you 25MB to start; extra drive space is about $100 a year per 100MB. A "Clip to Driveway" feature saves Web pages to your online drive.
Usability	Edged out in usability testing, Xdrive was actually the favorite service of half of our testers. It was fast enough, copying 10MB of files in 62 seconds, but the virtual drive letter feature was buggy.	Testers loved having 50MB but didn't find the site intuitive. It was the slowest of the bunch, downloading 10MB of files at 70 seconds.	Our usability champ by a slim margin. Testers praised Driveway's ease of use and fast transfers—completing the 10MB download in a mere 46 seconds.
Survivability	With 3.5 million members, it's the smallest of the bunch, though it has the most actual traffic. With $45 million in funding from Wit SoundView Ventures, the company (and your data) should be safe for years.	It's still early for I-drive. $18 million in VC funding so far, with a $30 million third round on the line. Has 4.7 million members and is growing fast; its business model based on paying partnerships could be a winner.	Driveway yanked its IPO in June but plans to reregister sometime soon. But with $43.5 million raised in January, the company isn't hurting. Driveway claims more than 6 million users.
Bottom Line	Best overall, it's easy to use and plenty fast. Bonus features make it a winner.	Slow and confusing. A little extra space doesn't guarantee happy users.	Loved the ease of use, but lack of extras makes Driveway an also-ran.