Hi, and welcome to the TDP forums!


You're right to be most concerned about lens choice - the lens has a much bigger impact on image quality than the body (consider - the sensor used in your chosen 550D is the same one used in the 600D, 60D, and even the 'prosumer' 7D).


If your budget will cover it, I'd recommend one of two lenses - theEF-S 17-55mm f/2.8 IS USM or theEF-S 1<span class="bbc_u"]5-85mm f/3.5-5.6 IS USM. Optical quality is substantially better than the kit lenses, and the focal ranges are excellent for general-purpose use. The 17-55mm has a fast f/2.8 aperture, meaning it's better suited to portraits and indoor use. The 15-85mm has a broader zoom range (one consequence of that is a bit more distortion at the wide end), but the tradeoff is a slower and variable aperture. Since you've used an 18-55mm lens with a slow/vairable aperture, you may have a good idea if you want more range or a faster aperture in your 'walkaround' lens.


IN addition to the body and lens(es), there are a few other things to comsider. One would be supplementing your general purpose zoom with a fast prime - a budget option like the EF 50mm f/1.8 II (aka nifty-fifty, a fast prime that's decently sharp although not well built, and is the cheapest lens in the Canon lineup), or a step up from that such as the EF 85mm f/1.8 USM. Also, consider an external flash (light from the pop-up is harsh, and IMO pictures taken with that look like they could have been taken with a point-and-shoot) - get one that allows you to bounce the flash off a ceiling (e.g. 270EX II, although I recommend the 430EX II if possible). Finally, consider a decent tripod - IMO, Manfrotto is the optimal compromise between value and quality (getting a cheap tripod just isn't worth it).


FWIW, I started out with a T1i/500D, 17-55mm f/2.8 IS, 85mm f/1.8, and a 430EX II, and was very happy with my kit. I have added a lot of gear to my kit since then, but I still have and use the 17-55mm - the lesson there is to get good lenses at the outset, since they'll probably last you through several bodies over time.


Good luck with your decisions!


--John