**Not just beef, eating any kind of meat is by default prohibited in Hinduism**. Consider the following statements from the primary Hindu book of law:



 1. Meat can never be obtained without injury to living creatures, and
    injury to sentient beings is detrimental to (the attainment of)
    heavenly bliss; let him therefore shun (the use of) meat. [Manu
    Smriti - 5.48]
 2. Having well considered the (disgusting) origin of flesh and the
    (cruelty of) fettering and slaying corporeal beings, let him
    entirely abstain from eating flesh. [Manu Smriti - 5.49]
 3. He who permits (the slaughter of an animal), he who cuts it up, he
    who kills it, he who buys or sells (meat), he who cooks it, he who
    serves it up, and he who eats it, (must all be considered as) the
    slayers (of the animal). [Manu Smriti - 5.51]
 4. There is no greater sinner than that (man) who, though not
    worshipping the gods or the manes, seeks to increase (the bulk of)
    his own flesh by the flesh of other (beings). [Manu Smriti - 5.52]
 5. He who during a hundred years annually offers a horse-sacrifice, and
    he who entirely abstains from meat, obtain the same reward for their
    meritorious (conduct). [Manu Smriti - 5.53]
 6. By subsisting on pure fruit and roots, and by eating food fit for
    ascetics (in the forest), one does not gain (so great) a reward as
    by entirely avoiding (the use of) flesh. [Manu Smriti - 5.54]

All these statements convey one and one fact only, abstaining from eating meat as it causes pain and suffering to other animals. Now consider the following two statements:

 1. One may eat meat when it has been sprinkled with water, while
    Mantras were recited, when Brahmanas desire (one's doing it), when
    one is engaged (in the performance of a rite) according to the law,
    and when one's life is in danger. [Manu Smriti - 5.27]
 2. He who eats meat, when he honours the gods and manes, commits no
    sin, whether he has bought it, or himself has killed (the animal),
    or has received it as a present from others. [Manu Smriti - 5.32]



So this is the thing regarding Hinduism, there is no one strict law. Every thing depends upon the context and intention. Hinduism informs you what to do and not do, but it doesn't command you to do anything in particular. The system of Karma takes care of all. Do whatever you want to do, but be ready to reap the corresponding result. This is the doctrine of Hinduism.

 - As many hairs as the slain beast has, so often indeed will he who
   killed it without a (lawful) reason suffer a violent death in future
   births. [Manu Smriti - 5.38]

Depending upon context and intention Hinduism even allows actions that are generally forbidden. So **the question you should ask yourself is whether you are eating beef out of rigid necessity**. Is there no other food available for you to eat? Are you eating it because it tastes good? Ask yourself such questions and then decide. Listen to what your heart says, not what logic says. If everyone is doing the wrong things, should you do them as well? Would you like to be killed and eaten by others if you were a cow or any other animal?