beginner roadbike <$500

try looking ant bikesdirect.com Happy shopping

That's a tough price range.  You're getting down to where any new bike at that price range is kinda' bottom shelf.  I'd suggest searching for a good used road bike, that was perhaps $1200-$1500  when it sold 4-5 years ago, without too many miles on it.  Think Aluminum, name brand, shimano 105 class.

Personally I'm not a big fan of used bikes unless you or an available buddy have some expertise and can evaluate the condition of a bike.  If it's thrashed or hasn't been maintained you can easily wind up putting a couple hundred dollars into it (tires, chain, brake pads, cables, bar tape, etc. etc.) just to make it safe and suitable to ride.

For new bikes, Bikesdirect.com is hands down your best bang for the buck.  If you can stretch the budget just a bit they've got a couple on offer for $599 that will at least get you a Shimano 105 rear derailleur.  If you really are limited to $500 they have several choices in that price range that are perfectly acceptable bikes with the best quality you'll be able to get for that money.

How tall are you? I have a Giant that I am thinking of putting up for sale. I need to move up to a larger bike. I would definately sell it for under $500. It is an XL, which equates to around a 60cm. PM me if you are interested.