To put it in perspective for you, my '79 Raleigh Pro (Reynolds 531) with a B17, full campy Record/NR gruppo and tubular rims (with not-especially light tires) weighed in at 23 lbs. My '88 Nishiki Modulus (Tange #2) with full Shimano Exage parts and Cheng Shin 700X23c tires riding a pre-softened NOS Brooks Professional saddle is about 23.5. One is top of the line, the other is a mid-level bike 10 years later. I'd say that you have a good weight there. Besides, it's been my experience that going much lighter than 23 lbs on a steel bike is approaching nearly too light. Then again, I'm a masher who rides my bikes like I'd ride a redheaded adulterer...dropping spoke numbers and going with lighter (and almost inherently) lighter parts would just lead to breakage with my riding style. I find that for an everyday bike with fenders and a B17 running about 27 lbs is perfect - light enough to toss, heavy enough that I feel it's a solid, long-distance performer.

ETA: Remember, lightening your rotating mass is a whole lot better than lightening the bike itself. In drag-racing, there's a formula that lists something like 5 lbs from your wheels lowers your 1/4 mile time by a tenth. In bike terms - get a bike and swap from steel to aluminum rims - you'll feel infinitely lighter, even if nothing else on the bike changes.

If you're looking at losing weight, I'd start with the tires. With 700c, you can go anywhere from 500g (or more) to 250g. It might not sound like a lot, but trust me, it is. Also, although it sounds counterintuitive, don't worry too much about tire width if you're already running 23c tires...20c feels faster to me, but I can't tell a difference with any swap from 23c to 28 or even 32c tires, except for comfort, which will make you faster whether or not you are losing any weight.