Will this lens work with a nikon d3000?

I currently have a pentax zx-60 and I'm going to be upgrading to a DLSR this weekend as my business is starting to pick up and I want/need the convenience of a digital camera.

I have this lens on my pentax:

http://www.epinions.com/reviews/elec-Photo-Lenses-All-Sigma_28_200mm_F3_5_5_6_DL_Aspherical_Hyperzoom_Macro

I'm not sure if it's the older model as my father in law gave it to me and he had the pentax for a few years.

I want to know if this lens would be compatable with the Nikon D3000 or any nikon DSLR

other models i've looked at are:
-canon rebel
-sony A330 (costco currently has this one w/two lenses, the bag, and a 4g card for 500 bucks)

which brand would this lens work best with? I love using it so don't really want to replace it plus I'll still be using the pentax as a backup.

No, it is not compatible.

The Nikon F mount and the Pentax K mount are not interchangeable.

If it is super important that you mount your Sigma 28-200mm f/3.8-5.6 Lens for Pentax to the D3000 then you might want to research adapters.

Did you know that Pentax makes some of the finest dSLR cameras on the planet? Why don't you get a Pentax dSLR for your Pentax mount lens?

Buy a Pentax DSLR then - the Pentax K-x is supposed to be very good and your lens will be compatible with it.

Your lens will not fit on the Nikon, Canon or the Sony - it's a Pentax mount lens!