I had QuicktimeTask always running in Systray. I disabled it with msconfig--> startup options, but it would always re-launch itself each time I used Quicktime (viewing movie previews online, mostly).
So I went into Program Files/QuickTime and renamed qttask.exe to qttask.bak. Problem solved for good!
Maybe you can try something similar with ITunes Helper. Just find the exe and rename it.