for roku unless you need the game stuff get the lower end model. Amazon has it cheaper. Does 1080P streaming but big warming it's really only useful for netflix. You may be better to get get the WD player as it's does netflix plus other file formats. I got one for my in-laws for x-mas. Tested it out I myself was not impressed with it but it does netlfix well and video looks good and it's easy to use so it's good for them.
On download media honestly I'd just build a small HTPC and install XBMC on it.
So if the HTPC is not something you're into I'd go with the WD player it will do netflix plus play downloaded files. Some files may give you issues but most should work ok.