Anything that rolls reliably, is in the proper shape of a road bike and is a good price is a good bike for a beginner. Stay away from mail order for the time being, you'd have no idea how to size the thing - size is important for road cycling; lots and lots of repetitive motion. 9 speed is fine, 10 speed stuff is still pretty expensive and you can still obtain 9 speed cogs and chains and they have fallen to pretty reasonable prices (can't beat a $30 9 speed 105 cogset vs. twice that for the 10 speed version). Tiagra is good for starters. It works in the same way as the higher price stuff and it will take you all the way from your first ride out the driveway to racing if you so desire.

My first new bike was an $850 bike which I got for $650 (the bike shop owner was kind and sold it to me for the price he (mis-)quoted me). I rode it for 9 years before I got a 2007 Trek Madone 5.2, which is an excellent bike. I still ride the old one; it is a rain bike for now. It is solid and is the most stable bike I own (I call it the "tank", because it is dead on stable and weighs a relatively "heavy" 23 lbs - quotes around "heavy" because 23 lbs isn't all that much heavier than 18, which my Madone weighs in at).

EDIT: I forgot to say that my very first bike that got me into the sport was a downtube shifting, 7 speed Trek somethingorother that I bought used for $300. Anything to get you onto the road - preferably in the shape of a road bike. Just make sure it doesn't fall apart and it doesn't break the bank.