OK, need advice....

I'm looking to pick up a hard tail MB this fall/winter to keep me riding when it gets too cold (for me!) to ride my road bike. I will also use it to explore some dirt roads, trails and go riding with the my kids. I am tired of constantly trying to "tweek" my $75 Wal-Mart special (Roadmaster!!.. why is it called that when its a mountain bike??) just to get it to function.

My question: The LBS I frequent and from whom I purchased my road bike has a Specialized Rockhopper comp for right around $750, and that would seem to fit my needs just fine. But what bugs me is that as I look at performance bike and they have an Iron Horse... the Maverick SE I think - that has almost identical components (front and rear derailuers are identical) for $450.

So my question - am I missing something? I know there would be no test ride or on the bike sizing from performace, but what would I be getting for an extra $300 from my LBS...besides a "brand" name? Anyone else go through desisions like this? I do like my LBS (get the 10% off rate, etc) but do order from performace/nashbar frequesntly.

Thoughts?

Odie1