Do you have the attachment for the XBox which allows you to control is using an IR remote? If so, you can use most One FOr All or Radio Shack universals (using DVD/0522). The code for your digital cable box is probably CBL/0476 (depending on the brand).
I've never heard of "Creative Extigy" so i an't help you there, but if it comes with an IR remote, you can always learn the functions to your new remote.
Your best guarantee is a JP1 compatible remote and cable.
[Link: hifi-remote.com][Link: hifi-remote.com]Rob