...or better yet...
Select files you want to move>right click>Library Tools>Move/Copy Disk Files>select your folder on the other drive and hit the Move button. All your playlists will be updated with the new file locations.
Your cover art should be safe if...
1) they are embedded in your media files
2) they are stored in a cover art directory that will not be moved
3) they are in the same dir as the media...since MC automatically assigns the first image it finds in a dir to the music files that are also stored there (ie d:\PinkFloyd\DarkSideOfTheMoon)...but it may do this only on files w/o defined cover art.
1 & 2 are bullet proof. 3 is problematic ( since the CA is not embedded, it uses absolute path references such as d:\PinkFloyd\DarkSideOfTheMoon\DSotM.jpg, which of course, is no longer valid if the whole directory is moved to e: )
10-27
edit: lee's solution may be better if you do the drive:\artist\album subdirectory thing. I don't bother. I differentiate audio files only by extension...so I have four directories on my s: drive called ogg, mp3, flac, and ape respectively.