Adding to what shawurai said, you can also buy a lot of VN's legally (both physical copies and downloads) here:
http://jastusa.com/If you want any more help with where to buy Japanese VN's (untranslated, but you can get patches for free for many VN's from groups who are translating them), then just let me know, as that is something I can help you with.
As for downloading game ISO's though...I can't help you, but like I said, I'm pretty sure that if you go and ask people in the cbox or on the #doki IRC channel, you'll quickly find somebody who will tell you where to download VN's, even if you're not able to search for good sites on your own. It should be easy. As staff members and official representatives of Doki, we can't help you with piracy since we do not support it, but it's not like we can stop anyone else from doing so. Well, we could if we set up rules and banned people for helping with piracy, but that would be extremely tedious, not to mention rather pointless, so nobody's going to want to do that.