MMm you really can’t rip them for songs and them use them for a comercial track, most of the time (depending on the original track) you will be having issues with ownership rights.
What I would recommend if you really want good quality voices is to just buy a voice pack. You will have plenty of options and all are royalties free so you can use them without guilt. I really haven’t find a free option man.
The other thing is that you should not be afraid of recording your own voice for other proyects where you need male voice. Voice is voice and unless is for singing (unless you are a great singer) your voice will work.
If you want female house voice you can check for some ideas.
A decent pack would cost around 40-50 US$ but it is worth it if you don’t have money to pay for a professional singer but still want a good quality end product.
if you do a search in most of the usual places (limewire, bit torrent etc) for “acapella” versions of tracks you can often find a fairly good selection, especially hip hop or r&B ones as these tend to be popular for remixing.
Not that I condone piracy or do it myself in any way!