PGP 7 interoperability - no luck

[Lars Hecking]

 I received a file attachment that was encrypted with PGP 7.03 (probably
 under Windows), using my public key:

$ tehran (109) gpg -d -o 666 6CF35589.data.pgp

You need a passphrase to unlock the secret key for
user: "Lars Hecking <lhecking@nmrc.ucc.ie>"
1024-bit ELG-E key, ID 9186116D, created 1999-09-22 (main key ID 83AC334A)

gpg: encrypted with 1024-bit ELG-E key, ID 9186116D, created 1999-09-22
      "Lars Hecking <lhecking@nmrc.ucc.ie>"
$ 

 but the decrypted file is garbage (should be a text file). Anything I can
 try? I cannot make the file available as it contains a virus.

 Note: I am almost certain this is not a MUA problem. The email message
 was not encrypted, only the attached file.