What does this email I got from SETI mean?

[perryinjax]

I got this from the SETI site and I do not understand what they are doing....what is the event? What is it's purpose? Please translate or explain what this is all about in layman's terms please?

Come howl at the moon with us and "hunt" for Top 5000 primes. It's a GREAT opportunity for you to find one for yourself! Who knows, there may even be the rare Fermat number divisor. We hope to establish a single day record for finding Top 5000 primes! At the last prime challenge we had a brutal battle to take first place between SETI.USA the new power house, Team Norway with SETI.Germany coming in a distant 3rd. This challenge is going to quick and a full on sprint from the start so having everyone possible crunching from the start will be the key to taking first place. Come on over and help us crunch for the win.

A 24 hour Challenge is being offered on PrimeGrid's Proth Prime Search (LLR) application. NOTE: Only PPSE work will be released during the Challenge. However, PPS resends will occur. All completed work, PPS or PPSE, will be credited in the Challenge score.

To participate in the Challenge, please select only the Proth Prime Search (LLR) project in your PrimeGrid preferences section. Application builds are available for Linux 32 bit, Windows 32 bit and MacIntel. These applications will be sent to 64 bit clients. As with all LLR application projects, there is no advantage of 64 bit over 32 bit.

RACE TIME 25 July 2010 18:00 UTC – 26 July 2010 18:00 UTC

Please follow us on twitter (http://twitter.com/setiusa) for the latest news and stop by the forum to get help participating in this challenge!

[gintable]

SETI received this message from the inhabitants of Gliese 581-d. What you are seeing is an anthropocentric translation of the message based upon inapplicable conventions of data storage.

[lithiumdeuteride]

SETI is partnered with other organizations which also use distributed computing (sending data out to various people, to take advantage of their CPU downtime). One of those organizations searches for prime numbers (numbers which have exactly two divisors: 1 and themselves).

[Mez]

I didn't realise SETI was into SPAM.

[Will]

It's an online competition between various organizations that use the combined computing power of their members' home computers. This one has to do with finding very large prime numbers.

[Man]

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