How to determine the entropy of a password

How can I tell if a password has good enough entropy to prevent brute-forcing on a realistic timescale? For example, if I have the following password, how can I determine if it is strong enough to prevent brute forcing?

"?e&ye&ga!ruaa!na!e%ta!e%rc#Iod$woH"2245

There's a site that can give you an estimated entropy figure for a password input. For the above example it suggests ~210 bits.

You can get a very rough guess of how long it will take to crack on How Secure Is My Password.

It suggests it would take a standard desktop PC 2 vigintillion years to crack the password in your example.

A more detailed analysis of the password can be seen on The Password Meter.

Your question - "Is it strong enough to prevent brute force?"

The real answer - "no"

The useful answer - "Probably, at least for the foreseeable future"

What you should be asking:

I need to protect this type of data, which has requirements x and y, and sensitivity z for my company. Is this an appropriate level of entropy.

Okay, to be fair, 210 bits as @Gareth pointed out is likely to be fine for a long time, but that may be overkill, and there are good reasons not to go over the top on encryption if you don't need to.