I think you're confusing your chips slightly.
There's the older Pentium dual core. Then there's the newer 'core 2 duo'. It's this core 2 duo that has been whipping AMD for some time now.

Currently Intel's newest consumer chip is the core 2 range.
AMD's newest is the Phenoms.

Previously Intel had the Pentiums.
AMD's prior chips were the Athlons.

I'm pretty sure AMD was beating Intel right up until the core2duo was released.

Now Intel's got Nehlam coming up, while AMD's new Phenoms don't even match Intels ageing core 2 duo.

The rationale you'll find most people using for one chip with the same speed, cache and number of cores beating another is 'architecture'. I don't know any more than that sorry.

just a question: what is the best brand for laptop when using core 2 duo?

That's a fairly broad question. It really depends on what's most important to you.

The 3 main features people look at are:
- Life of the battery (will it last 1 hour or 6 hours before needing a charge).
- Portability (is it really big, or really small)
- Performance (can it do fast calculations, and can it run games & 3D stuff).

I don't keep up with the laptop market, so someone else will have to suggest a brand.

Not Dell for sure

I have had a dell for a year or so now and never had any trouble with it. I would like to ask though why not dell? I am on the same side as well as i would not recommend dell to anyone either just for the reason that their unique parts are not available readily or cheap and most are dell branded. Pain in the back end for people like us who would rather shop around and find a good deal. What is your reason for that? I have never had to deal with dell customer service yet and I hope I ll never have to either.

I would go for Acer as they have a good build quality, reliable and not that very expensive either.

Raj