Just don’t be one of those silly folks who bring digital scales to the bike shop…while needing to shed more than a few ‘grams’ themselves. 
This is a valid comparisson, but consider too a beginner buying a racquet.
I’m new(ish) to squash and decided to buy my own racquet. Is lighter better? Generally… maybe. A lighter racquet is easier to swing around, and has good touch. But heavier racket can give you more control. Then there is also the question of balance: some people like a racquet that is head heavy, some prefer head light. Then there is stiffness: will a whippy racquet suit my stule of play?
Which racquet is right for me?.. How the hell do I know? I’m not an experienced enough player to answer any of those questions. I don’t know what my “style of play” is. I just know: “See ball? Whack it!”
I could spend a lot more on an ultra-light racquet, but will I benefit from its weight? I may find out that a heavier one with a bigger sweet spot gives me more control and that I’m simply way too much of a newbie to be fussing with a super-light racquet that requires more technical skill.
But we totally agree that the OP should invest in a lighter bike with good components, but going all out and getting one of the lightest bikes ($$$), might be premature.
Mine too. More than thirty years old, actually. It’s a 1974 Raleigh Super Course. It was, and is, a good frame. Reynolds 531 tubing (high quality chromoly steel). I’ve changed a few components, notably the crank, so I could reap the benefits of a triple, and the front derailleur. Also the wheels and freewheel. Other than that, it’s the same as it was the day it was born. Some wear items have been replaced – cables, brake pads, and the seat (but the seat is still an old-fashioned Brooks leather seat).
I ride it quite a bit. 60 or 70 mile rides are typical for me on weekends (at least in decent weather). I do a couple of century rides (100 miles) each summer.
My brother, a frequent riding partner, rides a modern Trek 1500. It’s a nice bike. I would never trade it for mine.
Carbon fiber is wonderful stuff. It’s also fragile (not in the sense that it can’t bear the stresses of riding, or transmit force from your muscles to the rear wheel efficiently, but if you get a ding on the frame, it can be the beginning of the end). And modern bikes tend to have considerably less comfortable frame geometry, being based on race bikes. An older bike is likely to be more of an all arounder. You’ll be able to get the bar tops level with the seat, or nearly so. The front wheel will be further out front, makeing the bike less twitchy. You’ll be able to mount a rack, so you can carry food and maps and a rain jacket. You can mount fenders.
Just something to think about.
This is what the helpful folks at my local bike shop said as well. Which is why I went in planning to spend around $700 and ended up spending $1,200 (I started out looking at the Specialized Allez Triple ($770 MSRP) and ended up buying the Allez Elite Triple ($1,100 MSRP - the rest of the money I spent was sales tax and accessories).
The Elite frame had a bit more carbon fiber to it (and a different type of CF, apparently), a better saddle, better/lighter handlebars, better derailleurs, and some vibration-damping technology. The “standard” Allez’s frame was based on a “road” design, while the “Elite” model had a “race” design (one of my stated goals was that I wanted to “go as fast as possible”, even though I don’t race, so this was a bonus for me even if I don’t know how much difference it actually makes. heh). Better components top to bottom. Also, 27-speed vs. 24-speed.
Specialized’s Web site was extremely helpful when it came to researching their different models, allowing me to compare everything side-by-side.
My only regret is the color scheme - I really wanted a red bike, but the Allez Elite was only available in silver/black and white w/red & black trim. But, since the paintjob doesn’t affect performance … But now that the 2008 models are listed on the Web site, I almost wish I had waited. The 2008 Allez Elite Compact is comparable to my 2007 Allez Elite Triple (actually a bit better) and is available in a completely awesome red & black color scheme (Team QuickStep colors).
One more thing …
Which isn’t to say I don’t like the color I ended up with. It actually looks much better “in person” than it did when I looked at the photos on the Web and in the catalog at the dealer (I had to special order mine, since they didn’t have one in stock in my frame size, and didn’t have any in that color in stock). The white is actually a deep, pearly white, which you can see in this larger version of the photo I posted earlier (warning: 726kb).
I have a folding mountain bike that I leave in the trunk during the summer. It’s very heavy when compared to my aluminum bike and is noticeably harder to pedal. While it would be nice to have a CF bike I would have to ride a lot to justify spending $1700. $500 buys a decent bike and you don’t need a body guard to ride it. I also have a bio-pace chain set which is fun to ride.