So basically I don't know anything about bikes and I'm posting this to get some advice from the PROS!! YEAH!
I've narrowed it down to these three mountain bikes that are in my price range and seem good for beginner but let me know if im wrong! I'd be using it for riding to work and would try to ride some of the easier bike trails here in SANTA CRUZ!
Raleigh Talus 3.0
Diamondback Outlook (found on amazon, i'd have to piece it together I s'pose)
Schwinn 2010 Frontier (they say it's great for a beginner)
My advice is, get the right bike for what you need it for. If you're going to be doing off road riding(I'm not familiar with the trails in Santa Cruz), and that's the main reason for getting the bike, then get a mountain bike. If you're thinking mostly about commuting on paved roads, I suggest you get a hybrid. Although many people commute on mtb and love it.
Go to a bike store, have somebody help you choose what you need and figure out your size. I wouldn't recommend buying a bike on line in your case, when you're not really sure what you want. Test ride a few different bikes and see how they feel.