However if you are beginner and plan to upgrade to better one in the future I would suggest 1000D.It is user friendly,easy to use but provide great images.Learn every things with it and save your money for another good lens.When you want to change to better,you can change only camera body and use with your good stock lens.

Second sometimes the “worse” one has mroe advantages over the “best” ones, such as less megapixels, which is actually a light enhancing secret,and noise reducing, and pictures over 6mp are clearer than you can see with your eye. even at 16×20 inches

Since you have recently taken this interest, i wouldn’t go all out to find out you don’t touch it but once a month for a quick shot of the fam. and one more note, the camera doesn’t make the photo’s the photographer does, these are just fast crystal clear images, i’ve seen amazing photos from 3mp nikon or canon point and shoots.

The HD video shooting is also an added bonus. It can shoot full motion 30 fps in 720p and 20 fps in 1080i.
Also, the camera is compatible with all the Canon EF lenses. Definitely a hearty bargaining chip.

The 450D naturally had a few improvements over the 400D. The 1000D (even though released after the 450D) is not better, because it’s missing some features found on the 450D. But, it’s still perfectly ok.

The 40D (released in 2007) and the newer, 50D (released in 2008) are not necessarily more advanced, but are dearer because they have a stronger, better built body, a few extra features, bells & whistles and better high ISO capability. They also are capable of faster frame rates, so are very suitable if you shoot fast action or sports. They are also larger and heavier than the others, so some people might not pick them for this reason alone.

As to which camera you should pick. Well, that’s all up to you, because only you can determine which feels right in your hands. The 450D or 500D would make a good first dSLR, so recommend either of them. They are available in a kit with the 18-55mm IS lens, which is ok for starters and once you have mastered your camera’s features and manual controls, you might want to think about investing in a better lens. Lenses are very important to your overall image quality, so make sure you choose wisely and you’ll have a good lens that will last you many, many years…

If it is a recent interest in photography then I would firstly take the 40D out of the equation It won’t be too advanced for you – it has pretty much the same settings as the other models. But the only real differences are FPS is faster (you take take more pictures in a second), it has better low light performance, and it’s better built. But you only need these extra features if you are a very regular user who is taking photography more seriously. It’s much heavier than the other models, and the extra money would be better spent on accessories for the other models.

The 500D has only just been released, making it extremely expensive. It is an excellent camera and the HD recording feature on it is very impressive, but is it worth the extra money? It will come down in price later on.

The 1000D is the new very entry level camera. I’ve only used one of these once. Its slightly better than the 400D in some aspects as it has, with liveview, slightly faster at saving photos (a better processor), But it has less focusing points.

The 450D Is pretty much the same as 500D (slightly worse low light performance and no HD video). It has a large screen, live view, and works really well. I would recommend this model to you.

The 400D is the same as 450D/1000D but has a smaller screen, and no live view. You can get a really good price on this camera. But the smaller screen can be annoying when reveiwving your photos. Personally I don’t use liveview anyway (looking on the screen to what you’re taking rather than through the viewfinder). But some people may miss it. I would recommend this camera if on a tighter budget, and again, the extra money may be better spent on accessories.

Whichever one of these cameras you choose you won’t be disappointed with, as they really are great. But the lenses that come with them are rubbish! They’ll be fine for when you’re learning, but the first thing I’d buy is an EF-S 17-85 IS USM lens. Its a much better general lens.

Eventaully you may also look at buying an external flash (430EX) which is more powerful and you can move the light source to face different ways making pictures with flash more natural and professional
Good luck!