X:drive and i-drive are similar in functionality. Both have you submit a form with your e-mail address, a user name, a password, and some personal information; in seconds you receive an e-mail confirmation that your account has been opened. Once you log in, you're offered a page that represents your "drive". The page looks similar to a Windows Explorer window; in fact, if you can navigate Explorer, you'll have no problem poking around in your virtual drive.
The two services are also similar in features. Both i-drive and X:drive offer the same basic storage and access functions: upload and download, create new folders, move, rename and delete. And both let you set up a space on your Web drive that can be accessed by others, for sharing photos, MP3 files, or any other data you wish.
Still, depending on your particular needs, you should consider a few things. If you regularly move many files around, i-drive makes the task easier, as its interface allows multiple file selection. If you don't think that's important, try deleting 10 files on X:drive; you'll quickly get tired of repeating the select-folder/select-file/delete/confirm-screen refresh cycle.
There are also some key differences in the applications i-drive and X:drive offer to facilitate shuttling files between your computer and the Web. X:drive's Windows 9x client program (an NT version is in the works) is more transparent: it creates a new drive letter that is accessible from Windows Explorer or any Windows program. If you have a high-speed Internet connection, that kind of convenience is hard to beat.
The i-drive Sync software (which works on Windows 95, 98 and NT) isn't as seamless. It works on a principle similar to Windows 95's Brief-case, or the Palm's synchronising software: once you establish corresponding folders on your PC and on i-drive, clicking the Synchronize button will transfer the appropriate files (including those in subfolders), keeping both folders up to date. Unfortunately, Sync can't synchronise file deletions; if you delete a file from your local folder, you'll have to remember to delete it on i-drive as well. Also, Sync remembers only one set of corresponding folders at a time.