I purchased a pair of audioengine 5 self powered speakers for my desktop and couldn't be happier. I hooked them up to my computer through a economical USB DAC and get very satisfying sound. They are probably not the last word in accuracy as the midbass seems fairly tipped up but that is one of the reasons I enjoy them so much. I have a subwoofer under the desk and haven't felt the need to hook it up.
There are so many choices in music via Winamp that I find myself utilizing my main system less and less.