Startup options (params) for services

I have several services running on Windows XP that require a long string of startup parameters. When I place this string in the proper field of the “Service Properties” dialog box, and then start the service, it works fine. The string is then grayed out in the field. Once I close the dialog and reopen it the string is gone.

Can anyone tell me if the string is stored in the registry and how one might view/edit it, if it is in the registry?

Thanks in advance! This is a pretty hot item for us.