a white subject on a landscpe shot in broad daylight is going to be tough. there are better photographers than me on here but for my 2c, here are some tips:
- pay close attention to light metering and tell your camera where to grab the light reading from. if it's averaging across the viewfinder, the sunlight will wash out your white subject.
- try and position yourself so the sun is behind you instead of shooting into the sun.
- use a uv filter or a polarising filter to cater for harsh sunlight. a gradient filter may also allow you to control the wash from the top of the shot.
- use a lens hood
- i know some people use a dual exposure filter to assist (especially for landscapes with bright skies and dark terrain) but they freak me out and i don't fully understand them.
the 400d is god's camera. i would buy one in a heartbeat if i had the $$$.
edit: hmmm, on second thoughts, the 400d is not god's camera, but it is blummin' good. and definitely go the canon over the sony.