If i had an image link from a high pr website , however there was no alt tag. Would this bring any improvement ( strength/ PR ) to the SEO of my site ? Thanks Tom
Yes it counts and improves PR but it has no "weigth" for any keyword - as there is none - except you have a keyword rich URL.
I Agree @ monfis, getting a link as an image or even a dot hyper-linked will add to your PR hunt Cheers