Hello, and welcome!

The default administrator account in XP is simply "Administrator". If it does not show on your startup screen, you can enter it by holding down Ctrl+Alt and pressing Delete twice. It will give you the old style login screen and you can use the Administrator name and the password you set up for it.

As for scheduled tasks, I'd check to see if you inadvertently checked the box that says "User must be logged on". If that's checked, then, well, you have to be logged on for them to run. Also, you'll need to specify a login and password that they need to run under, else they won't have permissions to do anything.

And finally, some programs just don't play well with Windows Scheduler, requiring complex command line entries to run unattended. Sometimes just running the EXE command will open the program and wait for you to do something. You have to poke around in the help files of your software to find out for sure (I've not used most of the software you listed).