No software is going to be able to automatically sift out the bits you don't want - how would it choose?
You can use Audacity (or any other sound editor) to fiddle with the EQ manually. You might be able to get rid of various types of sounds using the general noise removal filters. Also if you record in stereo and make sure that the mikes are pointing directly at the speaker, then it should be possible to remove extraneous noise by removing anything that appears in one channel and not the other. Frankly though, I think you'll end up working harder than if you took notes!
What are you using to record with? Last October I visited clients in the UK and did just what you are trying to do: recorded every meeting, whether in a conference room, restaurant or pub. I got pretty good results with a Sony NWD B105, which cost me 29 quid and is about the sixe of a cigarette lighter (are you still allowed to say that in the UK?)