If you can have 50 bucks than hd 4650 will be a really good option for you to use for the HTPC setup.....even for gaming(optional for you) it will be really good....
I hope 50 bucks are not expensive for you.....
Integrated video on most of AMD's current chipsets should be enough, other wise a 4650/4670/5570/5670 would all be more than powerful enough for the task.