One year ago I bought the 350D with a 17-85IS, which was my first digital camera. At that time I was quite happy with it, especiallyy the image quality but I wasn't happy with the 350D controls.
To make a long story short I sold the 350D with 17-85IS and went for the 5D with the 24-105 IS and I have never looked back. The image quality is outstanding and it has professional controls. The 24-105IS is a very good lens and a class better then the 17-85IS.
But beïng realistic, it doesn't make sense to buy a 5D while not using L class, or at least very good lenses. Other lenses simply lack sharpness and show a lot of vignetting, purple fringing etc. The 5D simply makes everything vissable, including lens flaws.
A good altenative would be the 30D with a 17-85IS or 17-55IS f2.8. There are many discussion about ful frame or not, I do like full frame while others favor 1.6 crop cameras to have more tele-reach.
ps.
When buying the 5D, you shouldn't sell your 50mm f1.4 USM. This lens combined with the high noise free ISO numbers makes it an excellent indoor/night setup.
Good luck