Don't listen to them about modding it. Once you get comfortable with it, go ahead and give modding (jailbreaking) a try. A ton of us have done it and it's easy to go back to stock if you don't like it. Personally I could never go back to stock because I use too many of the third party applications and I love the way my iPhone looks. The stock look is just too plain.
I highly recommend this case,
http://store.everythingicafe.com/con...4-22--2742.htm. I've got it and I absolutely love it. It gives you the protection on the phone if you want to slip it in your pocket, but also gives you a holster to wear it on the belt if you want. It's the best of both worlds and its' very slim.