Telephoto Zoom & Macro

Hi everybody

I have recently brought a Nikon D5000 with 2 kit lenses and must say how delighted I am with the image quality. I am now looking to purchase an additional lens, I am looking for any suggestions or advise as to what fellow Nikon users feel will be best for my requirements. I am looking for a telephoto zoom say up to 300mm with macro facility, any suggestions and things to look for would be welcomed, at the moment Sigma and Tamron appear to make lenses to fit my requirements, but will they give me quality I am looking for? there also appears to be many choices within those lenses as well, it's confusing. I suspect a Nikon equivalent will be very expensive. Looking for your help and advice. Many thanks in anticipation.