If this is a one time, or every now and then thing, you can use Notepad, or WordPad, or another app and do a find and replace on E:\ . That will work quickly and easily.
Otherwise, the export playlist function wasn't exactly designed for this. Luckily, the Handhelds feature was.
Here's the wiki entry on it:
http://wiki.jriver.com/index.php/SyncThe basic idea is, you tell it a destination (like your I: drive) and then pick playlists to put on it. In it's options you can tell it how to lay out the files (like in Artist/Album directories for example), where to put Playlists and what format to make the playlists. It's got options in the playlist area for relative path, with and without a leading dot, etc, etc. Test it out on a tiny little playlist and you should be able to find the correct combination for what you're trying to do. It's a pretty darned nice system. Oh and get started in Tools > Options > Handheld > Device Management > Add a Device
Good luck!
Brian.