Hello again,

So, I'll have a Nikon F80 (N80) in a few weeks, but still can't decide which lens I want with it.
I'd like a lens which makes it possible to do some landscape photography, but also portraits.
That's why I'd like a 24-135 or a 28-105
I've found the following lenses:

Nikkor AF 28-105/3.5-4.5 IF D
Sigma AF 28-105/2.8-4.0 Asf.
Tamron AF SP 24-135/3.5-5.6 Asf.
Sigma AF 24-135/2,8-4,5 IF Asf.

The Tamron is probably a little too expensive for me. But, what about the Sigmas? Are they worth the money, or should I just go for the Nikkon?
The advantage of the Sigma is ofcourse the 2.8 maximum aperture, but if the quality is really a lot less as the Nikon...

Anyone can help me out here?