What is it?
Creative CD Assistant Service - CTSvcCDA.EXE
What does it do?
CTSvcCDA.EXE - This is a service creative by Creative labs to help your CD drive. Every time you insert a CD Creatives Player will try to play it for you. I suggest removing this and using either the built in Windows Media Player or Winamp.
You'll want to keep an eye on this google search for any known viruses. The normal location of this file is C:WINDOWSSystem32CTSvcCDA.EXE