:smile: 580EX is currently the top of the line flash canon make... a good picture is about good picture and good light control.. a swivel head flash like the 580Ex and the 430EX let u have more flexibility on how the light is going to hit your subject. these hot shoe flash should be a good start before getting in more serious light systems such as studio flash or multiple flash systems. i highly recommend the 580EX as it is a commander unit (that means you can use it to command other canon speedlites, it allow for future upgrades and more power)
as for lens... if u plan to go into low light photography(dark alley, wildlife) ... the XT is not very well equipped for that... you should get something like the leica M8 or the higher-end canon cameras like the 30D or the 1DsMkII... this is because the XT has a smaller view finder and a less sophisticated autofocus system... the lens will "hunt" in the dark and you might just lose those special moments and manual focusing with a XT is almost impossible with the tiny view finder. the 50mm f1.8 is considered a fast lens (big aperture) so its a good start for a newbie... canon offer alot of great lenses and alot whole lot of the crappy ones too... the " L" lens (lens with red rings) , USM (ultrasonicmotor,lens with gold ring) lens , the IS (image stabilizer) lens. L lens or "luxury" lens are the best lens canon has to offer thus most very fast lens (great low light performance) are L lens and some of the L lens are weather sealed and dust proof, USM lens are autofocus lens that have fast, silent and accurate autofocus motor, the good USM lens use ring USM motor drive while the micro USM motor is just crap, the IS lens are lens with sophisticated electronics that allow you to shoot with lower shutterspeeds which otherwise cause motion blurs with a non-IS lens.
as for books, u dont really need any of them... just read up the tutorials and booklets that came along with your camera. my advice, join a photography club at your community and have fun with trial and error.
a few more tips. get an extra hard drive dedicated to store your photos... 10Mp files are quite big
get enough memory cards for your camera (i shoot in RAW and have multiple 2GB cards) usually one 4GB card is enough for a casual shooter.
always shoot in best quality unless u ran out of space.
get a good camera bag, lowepro provide best protection at affordable prices, crumpler and domke and camera bags that dont really look like camera bags which is good when travelling light and low profile.
get camera equipment maintainence tools, bulb blowers (get them from pharmacies instead from a photo store), lens tissue like the ones from zeiss, and micro fibre cloths (the type of cloth you use it to wipe your glasses)
if u have further questions, feel free to PM me