time estimate for brute forcing wpa2

Need to know some time estimate on brute forcing a wpa2 key with a length of 13 and only consisting of capitals (A-Z) and digits (0-9).

Planning to buy a HD5850 only for this job.

Is this worth the trouble or is it gonna more than a week?

(already a sorry if there's a calculator available somewhere or/and i didnt do enough searching)
longer than a week
I am afraid humans will be already extinct long before it processes the whole keyspace.
91403960 years only.
Ok got it! Wink

Got a bit wiser in these few minutes.

Thanks and keep up the good work!
what i do to get a rough estimate.

look up gpu speeds, i like to use http://golubev.com/gpuest.html
the formula (charset^keylength)/gpuspeed
use google to convert seconds to hours/days/months/years/etc., so from google search type:

((36^13)/60672) seconds to years

results: 89,094,215 years