Following up on JesterFortyEight's suggestion: Look on the old box to see what account the ColdFusion service is running under. On the New box, make sure that ColdFusion is running under that same service. Unless you went out of your way to change it after the new installation, the new installation will be running under a service account, not a user account.
If they are both in the same Windows domain, and the account is a domain account, then it will easy to add it. Otherwise, you will need to get the system admin (or put on your system admin hat if that's you) to create a local admin account on the new server that has the same privs as the one on the old system, and then update the permissions on the directory that the CFFILE is trying to access to allow access from the new user. Hopefully it was a domain account, which simplifies the whole process.
hth,
reed