HDTV Resolution With Front Projection Sets

What is the minimum recommended resolution for a projector to display a reasonable HDTV signal?
Are 1/4 HD projectors a wise choice for HDTV viewing, or are higher resolution sets needed?
Thanks

480p would be a starting point, however there are several other factors to consider when shopping for a front projector:
viewing distance-- can help determine screen size, projectors' throw distance, type of projector, projector placement
how do you plan to use it--determines projector type and capabilities
source components--determines projectors' inputs and resolution
budget--setting a budget gives you a reference point

answer these questions and i'm sure you'll find the projector that fits your NEEDS