Download Accesschk.zip freeware to check an accounts access to file system objects, registry keys, or services.

After unzipping the file and placing Accesschk.exe in a folder that is in your path, typing accesschk /? returns:

AccessChk v2.0 - Check account access of files, registry keys or services
Copyright (C) 2006 Mark Russinovich
Sysinternals - www.sysinternals.com

usage: accesschk \[-s\]\[-i|-e\]\[-r\]\[-w\]\[-n\]\[-v\]\[-d \[username\]
   -c     Name is a Windows Service e.g. ssdpsrv (specify '*' as the
          name to show all services)
   -d     Only process directories
   -e     Only show exlicitly set Integrity Levels (Windows Vista only)
   -i     Show object Integrity Level (Windows Vista only)
   -k     Name is a Registry key e.g. hklm\software
   -n     Show only objects that have no access
   -q     Omit banner
   -r     Show only objects that have read access
   -s     Recurse
   -v     Verbose (includes Windows Vista Integrity Level)
   -w     Show only objects that have write access

If you specify a user or group name and AccessChk will report the effective
permissions for that account; otherwise it will dump the security descriptor.
By default the path name is interpreted as a file system path. For each object
AccessChk prints R if the account has read access, W for write access
and nothing if it has neither. The -v switch has AccessChk dump the
specific accesses granted to an account.

Examples
The following command reports the accesses that the Power Users account has to files and directories in \Windows\System32:

accesschk "power users" c:\windows\system32

This command shows which Windows services members of the Users group have write access to:

accesschk users -cw *

To see what Registry keys under HKLM\CurrentUser a specific account has no access to:

accesschk -kns austin\mruss hklm\software

To see the security on the HKLM\Software key:

accesschk -k hklm\software

To see all files under \Users\Mark on Vista that have an explicit integrity level:

accesschk -e -s c:\users\mark