Helmet recommendations?

[Jennifer Thompson <jlthompson@earthlink.net>]

Okay, I admit it...I'm a total newbie to endurance, and have
been trail riding for over 20 years without a helmet.

I realize I've been lucky to not have my head cracked open,
so no lectures please!  I am changing my ways!

:0)

I am now going to purchase a helmet.  But which kind is
best?  I'm talking coolness and comfort here.  I'm in
Sunland, CA, where we ride in very hot weather and I don't
want to be passing out on the trail.

I keep seeing Troxels, but there are like 5 different
kinds!  I'd like the coolest, most light weight, and comfy
(but still safe) helmet available.

Thank you for any suggestions!  You guys are always so
helpful.

Jennifer