I have an i850.
RC1 saw it and installed the drivers and they appear to be fine.
Prior to RC1 I had to pull them down with Windows Update, but they also
worked with no problems.
The only glitch I encountered was that I had to point the printer to the USB
virtual printer port rather than to LPT1.
That was simply Start > Printers, then right-click Canon i850 and select
Properties, open the Ports tab and select USB. If it's not showing, try
clicking Add..