1) Your stocker is broken. Mine definitely doesn't do that mounted on a 300D. Call Canon to see if you can have it switched out under warranty.
2) The 17-40 is an excellent lens based on reviews I have read.
http://www.photozone.de/8Reviews/index.html
http://www.the-digital-picture.com/R...s-Reviews.aspx
You can't really go wrong with any 'L' lens. I spent the extra and went for the 17-55 because it is faster (f2.8) and has IS. The 17-40 is arguably the better investment being 'L' and EF mount and not EF-S. I just hate using flash, so f4 is too slow at usable ISO speeds on the 300D and IS on the 17-55 also really helps with this. Image quality is on par with any 'L'.
Neither give you the same extreme wide angle of the 10-22 which goes for similar money as the 17-40. 17mm is approximately the same as your stocker.
3) As for letting other people hold your camera to take snaps of you and your BF, you won't be doing that when you have $1000 of glass mounted. That's what your P&S is for!!