The OP asked for opinions on the lens, i gave my opinon as did others.
I suggested that if he could possibly stretch his budget further then he should consider it as even as a beginner with a 300D i was disappointed with the Canon 75-300.
I also mentioned the Tamron zooms, which you seemed to have conveniently ignored for some reason.
The Tamron 75-300 LD Macro gets 7.5 / 10 over at Fredmiranda.com, which i generally find to be a good indicator of quality. That lens is available for less than £100 in the UK and going by the usual UK/US pricing, would be in the price range of the Canon 75-300 non IS.
Having owned the Canon, i know where my money would go if i were looking for a lens in that price range.
Now is that fair enough for you?
Sorry I was referring to your earlier post stating that your $400 Sigma was considerably better than the $159 Canon. You'd hope it was.
I missed your reference to the Tamron lens, sorry. Yes, this would be a much more fair comparison on budget. I don't have any experience of it so I cant comment.
BTW I think your original post was fair enough too. You get what you pay for with lenses most of the time. Stretching your budget will nearly always improve quality.

