Most of them are probably there from programs running when you start you computer. If they aren't programs you necessarily need running (Firewall, anti-virus), then you can try remove them this way. Go to Start > Run > then type "msconfig" and hit enter. Click the startup tab, and remove some stuff from there that you don't need and is showing up in your tray. If you aren't sure about what some things do, just post them here.