Mountain Biking - helmet help asap

whats a good helmet to get. i am going riding tomorrow and i need to know a good helmet to get.
i was wondering if something like this is any good. Helmet (http://cgi.ebay.com/ebaymotors/Motocross-ATV-helmet-L-400-ex-BMX-XR-250-cr-atc-xl_W0QQcmdZViewItemQQcategoryZ10066QQitemZ4564706712QQrdZ1)

not good, mostly because there are like zero vents so you will get hot as hades. Also if a full face isn't always necessary. I use one because I like the extra protection, but it is noticably warmer and heavier than a regular mtb helmet.
I might suggest digging around here
http://www.mtbr.com/reviews/helmet/
a friend of mine just got the animas. If your looking cheaper though, it's understandable. Just be sure to get something you like or you won't want to wear it.

also the guy might have crashed with that helmet, you never know.

You'd be better off dropping $20 at X-mart

just dont buy a used helmet, because youll really regret forking over $15.00 and your bones, when you could have been a little more liberal with ur money, and more conservative with your safety.

If your head is only worth $15 then get a $15 helmet. I like to think that my noggin is worth more than that though so I prefer to spend a little extra money and buy something that I can rely on.

For what it's worth I use a Giro E2 and a Giro Atmos. It is not necessary to spend this much money on a helmet but it is worth it to me. I like a comfortable, lightweight helmet with as much airflow as possible.