First, with EFS one does not encrypt folders.
One can set a folder so that any files stored into it
will be encrypted, but the folder itself is not encrypted.
Next, what ETS keys are needed in order to view an
encrypted file in the clear can be determined by looking
at the file's EFS thumbprint. This is within the properties
of the file. You may see only your info, or you may also
see info for a data recovery agent. Anyone that can log
into your machine and have the one of EFS keys corresponding
to what you see listed is who can access your files.
If you are in a domain that does have a functioning data
recovery agent, then someone that logs into your machine
with that account will be able to access your files.
If you are in a W2k3 Active Directory, domain level
administrators may have other options that they could
use based on whether your EFS cert/key was escrowed.
But keep in mind that potentially any account can access
the files, if it has the needed EFS key loaded.