In the light of the confirmed case of BSE in Scotland, is it safe to eat beef?
From the linked article, there is a non-zero risk to human health if eating beef infected with the Mad Cow disease.

"There was nationwide alarm following the confirmation of the first deaths caused by transmission of BSE to humans in 1996. At the time there were fears that hundreds of thousands of people might die as a result of eating infected beef. 

As it turned out 178 people have died of the human form of mad cow disease, known as Variant Creutzfeldt-Jacob disease (CJD). It is believed that these individuals were genetically more sensitive to succumbing to the disease than the wider population.
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If uncertain, make certain your butcher shop has verifiable traceability of all the meat he/she sell, so you can know where the meat comes from.

I think the information should be publicly available at your butcher shop.

Elsewhere, well, in Europe and North America, the standards are very high, so I would not worry that much; I can't say anything about the rest of the world as I don't know enough.