I rarely download anything, as I think that the less you have on your system, then the less likely something will go wrong.
However, if I am looking for something I particularly want, I usually start at cnet. The search bar in Opera (my preferred browser) actually has cnet search built into it. One word of warning though. Before downloading anything from cnet, always check that it isn't spyware and NEVER choose a program solely on the strength of cnet's "User Ratings". I strongly suspect that many programs available on cnet are repeatedly rated by their own creater, so as to make them look invaluable, when in reality they are useless spyware junk. >