hi Mak1168
i suggest you give this a try:
run your application as a windows service.
a link from Microsoft is here:
How To Create a User-Defined Service (
How To Create a User-Defined Service)
Setting an application to ruin as a windows service ensures that that particular program is automatically running in the background (even if the user is logged-out), and it ensures that the program will persist to run even if it has been manually closed. Running as a Windows Service also has some options to the program in the background and (i think) it has options for hiding the executable name of the program in the task manager
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If you want an easier third party app, i suggest try using "
Firedaemon" (
Run Any Application As Windows Service, Monitor Windows Service, Service CPU and Memory Usage | FireDaemon)
Summary: i have previously used Firedaemon for automatically running a "bot" program for the game Ragnarok (haha, please dont laugh, i once took playing and botting ragnarok very seriously!)
Firedaemon allowed me to choose the executable program, allowed me to choose a schedule for running it, and options for hiding the program in the background. Also, in my tests, the program runs even when no user is logged-in to windows xp.
Some screenshots of Firedaemon:
This is the screen where you set what program that is to be run as a windows service:
These are the settings where you can set the program to be visible
The Firedaemon website also mentions that their software is also used for:
1. Automating the startup of Game Servers
2. Java and other programming software that needs to be always-on
3. Business (analysis programs)
4. Networks (network monitoring programs)
5. "Server" software like FTP, EMail, chat servers etc.
6. Download software (yeah, so you can set your p2p to persist and always run in the background)
i hope this helps
******
Also, there is this "TrayIt" program that i previously used
TrayIt website:
http://www.teamcti.com/trayit/trayit.htm 
Install TrayIt and run the program that you want to be hidden from the taskbar. then use TrayIt to make windows remember to hide that program from the taskbar.