Deleting songs downloaded to my iPhone...

Hey all,

I had to sync my iphones itunes library to another computer and I downloaded all the purchased songs to my phone (didn't really thing ahead here) and now I can't get the songs I don't want off phone even though they aren't checked to be synced to my phone. How do I get the songs I don't want off without having to erase the whole thing and start over? I have a lot of contacts on there I don't want to lose, and I don't know if doing a 'restore' will just put me back where I was in the first place.