Road Cycling - new to bicycling, in search of a proper bike for daily

i just started riding two weeks ago and im hooked. i ride everyday for at least an hour before i go to work. i own two bikes, a vintage schwinn speedster and an old schwinn sprint i got for free. the speedster isnt practical for what im doing now but the sprint isnt that great of a ride either but its all i have. unofficially it weighs over 35lbs. my goal is to get in strong and in good shape so that i can ride my bicycle to work instead of driving (work is about 10+ miles away).
ive been shopping around and hitting all the bike stores as well as ebay. id like some advice if you have any on what type of bike i should be looking for and what i should stay away from. i saw a cannondale r400 at a local shop for around 750 but id like to go cheaper if i could. i also found some bikes on ebay, like the merida 900 that are selling for under 400... but im skeptical. should i just wait it out and ride till i kill the schwinn or is it just holding me back?

any help would be appreciated. thanks!

Best deal for a commuter is a bike from a garage sale.

Got my current commuter for $40 on a garage sale--have spent some $150 retrofitting it for commuting...now it is perfect!

hmm... so is it too soon for me to get a nicer, lighter bike? because i already have that schwinn... what modifications did you make to it for commuting? is the cannondale r400 not a good choice for my purposes? or am i getting ahead of myself there?

You'd probably want to go for either a used Touring bike or a nice, durable steel frame.

I personally wouldn't try to save 1.5lbs on a commuter by moving to Aluminum. The sacrifice in durability and comfort just isn't worth it.

A Trek touring bike could be a very good start...

First find a good route. Look at road conditions (potholes, glass, etc.), hills, traffic lights, intersections, number of lanes, etc. Then determine what type of bike will work best: road, mtn, hybrid, touring.

You might want to search or ask questions about commuter bikes and accessories on the commuting forum.
http://www.bikeforums.net/forumdisplay.php?f=20
Good luck.

For a 10mile commute, the best style is probably a light-touring/sport bike or a cyclo-cross/touring bike like the Bianchi Volpe.
You need fittings for luggage rack and fenders, and room for wider tyres.
If you leave your bike locked outside all day, then it helps to be a beat-up looking old bike, but you can use a high quality, light one.

i guess i could put some money into the sprint in order to better fit my purposes... i dont think i would need the luggage racks and things like that. im a cook, so i just need to show up.
the reasons ive been looking for a new ride are:
a) the sprint is pretty heavy (over 30lbs, not quit 35lbs like i originally thought)
b) the bike feels a bit small to me ever since i raised the seat to a proper height and switched out the drop bars for a straight bar. im constantly braking downhill because it feels like i could go flying over the handlebars at any given time. i measured from crank to seat post: 49 cms... and im about 5'7.
c) the bike is just old. all its components are old. the bike is a frankenstein creation. im sure that some of those 20 year old parts are to blame for the weight. the frame is straight and rust free though...
d) ive been interested in maybe converting the schwinn to a fixed gear and having a newer geared bike. but i guess ill wait on that first.

i recently purchased a lot of new stuff for my future (?) bike. maybe it'll all wind up on the sprint. i bought nitto mustasche handlebars, and some composite time atac pedals with rampas to match.
is there much i can do to make this bike fit me better?

What you'll want to do is go to your LBS and get fitted. Makes picking a bike much easier.

Another suggestion, take a look at the Surly Crosscheck. Very durable and popular for commuting...

Most of the thought behind the "commuter bike" issue usually revolves around the problem of carting a bunch of stuff with you. Since you are not worried about carrying books, papers, etc., then you can pare down your needs to just emergency equipment. That includes tools, tubes (or patches), pump, etc. to get you going again in case of problems. You may also want to carry rain gear in case the weather changes. The tools and such should be small enought to fit in a seat bag. The rain gear should be able to fit in another small bag (e.g. a handlebar bag to avoid the need of a rack). If that's all your really need, then why not get a nicer road bike if you want. My Trek 1500 (see posts elsewhere) is loaded down with a rack, panniers, etc. for my commuting needs, but strip all of that crap off and you've got a light, fast, fun to ride bike for $1000.

Too much? There are a bunch of entry level road bikes out there that are light and no doubt fun to ride. The best bet is as suggested above; check out a couple of LBS and take a few test rides. Since you should probably buy from your local LBS, especially if you are new to cycling, don't get too worked up about brands until you see what the LBS carries.

For 10 miles each way, you should stay away from MTN bikes, however, since the rolling resistance of the fat tires will make you work much harder than necessary on paved surfaces. As always, your mileage may vary...

Another advantage of a touring bike is the fender attachment braze-ons, that allow you to easily attach fenders to your bike. You don't want to sprayed with cold, dirty water every time it rains. In addition, touring bikes are solidly built, since they are designed to carry fairly heavy loads of panniers or even trailers.

The braze-ons are a good point, especially if you think you might add a rack in the future. Touring bikes are NOT the only bikes, however, that have them. Many road bikes these days do not indeed have them, so you should keep this in mind. The Trek 1000 and 1500, for example, do have them.

I know that people also recommend fenders for riding in the rain. I haven't made up my mind on whether I want to try putting them on my bike. So far, in my opinion, good rain gear is the most important thing for a road bike. Fenders might reduce the amount of post-rain clean-up required on the bike, but riding w/o fenders doesn't bother me directly as I don't notice appreciable road spray coming up onto me.

One more problem that I found in considering a touring bike is finding a dealer that even has one in stock to look at, let alone having one in your size. The economic facts are that touring bikes are not popular these days, so dealers are unwilling to stock them.