Just to add to all the comments given, go to a shop and handle the cameras and see which is the most comfortable to hold for you. The 350D is the smallest and the D50 the largest with the 5D somewhere in between. If you have big hands, holding the 350D will be too cramped, but if you have small hands, the D50 might be too fat for comfort as well. You mentioned you intended to keep it for a few years, and as mentioned by a lot of the folks, with an SLR, you are likely to end up buying bigger and HEAVIER lenses, so if the grip doesn't fit your hands,..... CRAMP......
Another point to note, the flash for the D50 pops up automatically, and even when up, if in auto mode, if there is enough light, it wont fire, whereas for the 5D you have to manually open the flash, and once its up, it will fire regardless, depending on your preference this can be either a negative or positive thing. Also focus assist for the D50 is a seperate light, but the 5D uses the flash. For me, came down to the D50 or 5D, (350D too small for my hands) and the AS swung it for me to buy the 5D.
Think whatever you get, you will have a good camera. Anyway good pictures depend more on the photographer, I've got a 5D and I love it, but can I produce photos as good as EOW?? Not now, and maybe never.