Hi David. What are you going to do with your bike?

Just ride to Grandma's house 20 miles away?
Ride strictly on roads or paved trails?
Ride it on rock-laden dirt trails in the middle of the woods?
Race it? If so: On road? Cyclocross? MTB racing? Track/velodrome? Alleycats?
Pack it with camping gear and go on a 5-day tour far from home?
Set up ramps in the street and jump them while trying to do 360s in mid-air while drinking Mountain Dew?
Fold it into a suitcase and travel from France to China?
Just tool around town every so often at a leisurely pace, emphasis on comfort?
Grocery shop with it?
Commute to work, perhaps locking it up for 8 hours at a time?
Etcetera?

There are so many different bikes for different things, and so many of them are going to put you in a different position on the bike and have a different feel to the rides, some comfy and slow, some stiff and speedy, some in between.

You can find a decent bicycle in the $500-750 range, depending on what you want to do with it, but what do you want your bike to do? Lots of new riders who have no intention of ever racing or putting on the spandex get sucked into the idea that they should be buying the so-called "racing bike," but it's not the most practical bike for more pedestrian uses and abuses, nor for comfort. It's maybe good for the fitness freaks and people who place a premium on speed while riding on pavement, but outside of that, you might want something totally different - particularly if you don't feel personally slighted if someone dares pass you.

Then there are people who buy the mountain bike with suspension fork and never once take their bikes off the road. Good in the sense that it can take a beating, but if you're just going to gingerly ride it down the road, well.....

I've found that the most Goldilocks-style solution for my needs is a true touring bike. It can take punishment, it can be laden with bags and gear for picnicks, camping, or groceries, and it's pretty roadworthy yet not completely incapable of off-roading. It's not fast, but it's comfy and it's faster than most non-racing bikes. That's just me though.