I agree with Melanie, Terragen can produce probably the most lifelike landscapes of all. Here's a render I made in about a half hour (shrunk by about 50% to save room). I believe the only real differences between the trial and the registered version are larger render sizes and a special high-quality anti-aliasing, so be sure to check the trial out.

my DeviantArt page: http://snowsultan.deviantart.com/

 

I do not speak as a representative of DAZ, I speak only as a long-time member here. Be nice (and quit lying about DAZ) and I'll be nice too.