Here's your problem, I believe:
quote author=jklangen
I am using the GUI version of the tool which executes the command:
xcopy "C:\Users\My Name\My Documents" "K:\My Documents Home 071310" /D /S /Y
/quote
Lose that "My" and the space. Default W7 location for documents folder is [Drive:]\Users\Name\Documents. "My Documents" is a "special folder" that does not actually exist, that is attached to each user account.
I don't mind people knowing my name...
C:\Users\Mike>dir /w "c:\users\mike\Documents"
Volume in drive C is Win07
Volume Serial Number is E4DB-A92A
Directory of c:\users\mike\Documents
[.] [..] [amazon] [antivirus] [Ask and Record Toolbar]
[Attachments] AutoHotkey.ahk AutoItImage.jpg AutoItImage2.jpg backup.log
[Barbies Documents] blackbox-keys.txt [blank pages] [blueyonder ISP] [Booklet]
[Bookmarks] [Business Card] [cable modems] [Canon IP4200 printer] [cat stuff]
cc_20070426_0924.reg cc_20091225_135955.reg [cd dvd covers] Copy of backupN.log [coruna]
[CTI] [cuisine] [custom papers] [CV 2005] [Downloads]
[ellion dvd player] [eMule Downloads] [French] [GomPlayer] [Hays]
hello.txt [Historias minimas] [house repairs] [html] ISO1_DVD.nri
[Jobs] [Jobseekers Allowance] [letters] [lexmark] [maps]
[misc-doc] [Moyea] [My Albums] [My Data Sources] [My DVD Backups]
[My Library] [My PSP8 Files] [My Recordings] [My Virtual Machines] [Newsbin Download]
[newsdata] [Nick web page UNL] [nvq] [PassMark] [pc-tech]
[Phone numbers] [photo paper] [PINS vacancy] [printer test pages] [pwd-prot]
rss.xml [rwin calcs] [seagate] [Seagate Hard Drive] [SmallBasic]
[SnagIt] [SnagIt Catalog] [spreadsheet] [ssa spec doc] [st62k manual]
[Sustrans vacancy] [test] [The KMPlayer] Thumbs.db [TV Licensing]
[Vacances] [Virtual Machines] world.txt
13 File(s) 1,880,329 bytes
70 Dir(s) 74,851,790,848 bytes free
C:\Users\Mike>dir /w "c:\users\mike\My Documents"
Volume in drive C is Win07
Volume Serial Number is E4DB-A92A
Directory of c:\users\mike\My Documents
File Not Found
C:\Users\Mike>