What can/cannot be disabled

I want to speed up my computer start-up performance, so I've went into system configuration then the startup tab. What I want to know is what is safe to disable and what isn't? Here is a list:

Intel(R) Common User Interface (igfxtray.exe)
Inter(R) Common User Interface (igfxpers.exe)
Microsoft Windows Script Host
Synaptics Pointing Device Driver - (this is the touch pad isn't it?) If it is - I don't use the touch pad at all.
Power Management (Acer)
Microsoft IntelliPoint
Realtek HD Audio Manager
HD Audio Background Process
Launch Manager (LManager.exe)
IAStorIcon
I also have Acer Backup Manager but that appears to be disabled already.

So which ones is safe to disable? I'm certain that Realtek is the systems audio devices. Personally, I don't need them at start-up, but the question is what ones are safe to disable? I don't want to cause any issues with the computer. Thanks.

Install Microsoft Security Essentials
now and run a full scan.

Leave everything else unchecked. They are freeloaders on your startup, RAM, CPU and spy on you.

Thanks whs and gregrocker - I have disabled them all.
In regards to antivirus software, I have Norton360 so I'm protected.
Thanks.

See image here. I have configured Norton to aggressive at start-up. Should Norton be showing up in the start-up panel? Because Norton is showing that it is secure, etc.

Thanks then guys. I will mark the thread as solved.