I want to fully protect my computer and need some advice

I will be using the computer at a University next year

Should I get an Internet security suite (ZoneAlarm or Bit Defender)

or should I just go with Bit Defenders Antivirus and use windows defender with a spyware software like spybot?

suggestions?

I want to base my decision off of which choice will keep my laptops system resources for my use—-not for the security running in the background

I have Norton 360 installed on my computer but it takes up to much system resources thus my computer goes sluggish. I was wondering what was the best internet security suite out there.
Also, can you tell me what is (alone) a good AV, Anti Spyware, Firewall, etc. programs that I can use instead of the bundle suite.

Is it better than kaspersky?
Is it low on system resources?
If you think it is better than kaspersky please explain why it is better.

I am currrently using kaspersky internet security 2009 on 1gb of RAM