Upgrade Canon Body or Lens

[MonArk]

Hi everyone,

I am currently using a Canon 350D with the 70-200 F4L lens. Ignoring compsition issues, lack of experience etc. I can't say I am overwhelmed with the detail even after adjustment ( I always shoot RAW). Part of the problem of course is that the 200mm length is still not that long and cropped pictures inevitably reduce IQ(or is it inevitable?). I am therefore considering a secondhand purchase:

1. Upgrade lens to the 100-400mm L series,
2. Upgrade body to either 450d, or
3. Upgrade body to 40d.

The 40d feels lovely but I understand it has the same sensor as the 450d and so I wonder if the image quality is actually any different. (I have heard it suggested that the metal body reduces shake vs the plastic 450d) but even s/hand there is a big difference in cost. If I trade in my 350D my net outlay on the 40D is going to be about £250 - £300 but only £200 or so on a 450D.

If I trade in my 70 - 200 for the 100 to 400 (both without IS) then my net outlay will be about £200 to £300. (I think)

Your thoughts would be welcome.

Thanks