What lens(es) do you carry with you?

I have 6 camera bags now. In my Domke that is just as small as you can imagine to fit my 20D with 24-70L with hood reversed is my take along bag. Can't fit anything else in it.

But if you are talking just out for the day and may shoot something close or something far away, my new line-up in my Velocity 9 bag is 20D, 24-70, 70-200, 17-40 and 580. That about covers any possibilities.

I think you are asking for reasoning for an expensive purchase and want to make a smart decision about which lens to get to cover what your A620 has been giving you. I have the A510 and it's similiar, covers a lot and can be very portable. You will not get the same sharpness and range from any of the Dslr's or lenses suggested to you. You also won't get too many flat pictures and you will get wonderful bokeh. You will get control of exposure and range. You have to decide if this Dslr business is for you because it will be expensive and take a lot of learning time. Asking questions is good, but actually deciding and shooting is the only way you'll find out what will work for you. Have fun with it! Don't agonize. Just shoot! Then post pictures and we can help you out there as well.

I carry the 28-75 2.8 (Tamron) on the camera 90% of the time since I bought it

If I had a 24-70 or similar I'd probably just carry that with the 580EX around all the time but as my 17-85 is really poor in low light and hasn't got real small DOF when I want it I carry the 50mm 1.4 too. So 17-85, 50mm, 20D and 580EX is pretty standard. That's basically my whole kit at the moment.

I need the zoom for the versatility and for general shots of things that don't require any special aperture and are more about framing and "just being there" - the 50mm is for portraits, low light work and artistic stuff mostly.

100-400 & 10-22 before i had to sell

This depends on where I'm going. Usually I carry in my back pack everything in my sig except the 75-300 & 18-55 kit I almost never mount those lenses so they stay home. If I just run out for a quickie, I'll mount whatever lens I think I need...the 10-20, 28-135, 70-200 or 85. the first 2 are used most. Almost always you'll see the 580 on top.

I just have all my gear in my Nova 3 AW and go from there

I take my 17-40mm most of the time. For countryside traveling, I also bring a 100mm macro for both macro and tele uses. I sometimes bring a 50mm for low light works too.

I used to carry my 30D and 24-105mm IS L with my MF Pentax 50mm 1.4 in a side pocket of my bag. I sold the IS L as I mainly used it below 50mm anyway, good lens tho', so now carry the 17-40mm L and Pentax with 30D. That's really my day to day convenience kit. If I want to mix things up and enjoy myself more I will take my Zeiss 35mm, the Pentax and the Zeiss 135mm.

I've got a 350D with a 50mm f/1.4 attached to it, and if I need to go wider, I've got a 15mm fisheye and if I need more reach, I've got a 200mm f/2.8. And a 430EX and a rocket blower. Though I'm thinking of selling the flash since I am what most term "an available light fanatic." All of this fits, with room to spare, in a Slingshot 200 AW.

What I carry varies with what I'm shooting. Lately, for dogs and travel, main gear bag (F802) has 15-30 Sigma, 24-70 L and 70-200 L IS, the last 2 mounted on 5D and 20D (which on which varies), along with 1.4x TC, 12 mm tube, the 580EX and a full set of polarizers and ND grads. 100-400 gets added on for air shows, hiking (wildlife) (moves me to the F-1X). If I see a need, I may toss in a 35 f/2 or 50 f/1.8.

Wow! Thats quite an arsenal Jon.
If I get the kit lens with the XTi then what would you (and others, of course) recommend as a good secondary lens, keeping in mind that I really would like to learn and do most of my work with 2 lenses and not a 3rd...at least at the beginning.
I do like to shoot landscapes, flowers, airshows, animals, buildings and although I have not done much low light and night shooting I know I will want to, and next year I will certainly want to shoot fireworks.

Jon carries it all in his Domke bag and knows how to use it all.

Fireworks are fun. Just make sure you are sitting in front of them and not under.

Usualy my bag goes everywhere. Canon 20D +grip with 17-40 f4, 70-200 f2.8 and 430EX
I usualy end up using both lenses for all my shots. I like the variety in perspective.

I usually carry everything you see in my sig (with the exception of the bodies, I use the 5D primarily), but when I dont lug all that stuff around I am usually carrying the 24-70 or 70-200 depending on where I am going.

Action=300f2.8+70-200f2.8Lis
Landscape=17-40,24-70.