Hi,
The PIX 501, that is the only command you need.
Is that your PIX only have DES encryption key?
If in that situation, I think in the 3005 , you shoose"IKE-DES-MD5" is the IPSEC SA in the group settings.
Please goto "Configuration | System | Tunneling Protocols | IPSec | IKE Proposals | Modify"
Modify "IKE-DES-MD5"
Change "Diffie-Hellman Group" from group 1 to group 2
Because easy VPN client using group 2, VPN 3000 concentrator default for DES is group 1, for 3DES is group 2.
If you do not change it for DES, it will fail in the ISAKMP negotiation.
Best Regards,