Sigma vs Tameron vs Nikon for 70-300

[Gagan-The-Dragon]

Hello people of the Photoforum!

So am looking at acquiring two new lenses for my Nikon D3100 (currently I am running with a 18-55 Kit lens)

One of my choices is the Nikon 50mm 1.8, that is set in stone.

However, I was looking for a zoom lens to have along with me as well so I have all three aspects covered for a beginner photographer (50 for fixed, 18-55 for wide, and a 70-300 for zoom).

Now I came upon the Sigma 70-300 APO
(5A8306 Sigma 70-300mm f/4-5.6 APO-M DG (Motorized) Macro Telephoto Zoom Lens for Nikon AF D Cameras - USA Warranty)

and the Tameron 70-300
(AF276N700 Tamron 75-300mm f/4-5.6 LD AF Macro Auto Focus Zoom Lens with Hood for Nikon AF D - with 6 Year USA Warranty)

Now I know Nikon has their own 70-300, but I am running on a tight budget as a beginner and Nikon's VR 70-300 is fairly pricey for me.

So I was wondering if any of you guys could provide some insight on what direction I should take here, if any of you have used either of those lenses, the Tameron or Sigma. I know this Sigma does not have image stabilization, the one that does gets up there with the Nikon price.

Or should I aim at possibly a lower range? The Sigma 50-200 does have optical stabilization.

I was (and still) researching the different lenses to see what info I can pull up, and any information you provide will be extremely helpful.

Thanks!