I’m not sure how much you’ve looked into this, so I can’t be sure how much of this would be repeat for you. I’m actually kind of at a loss for how you can come to anti-IP views without being versed in the responses to these common questions. But try these on for size:
Intellectual Property at Mises.org
Obviously Kinsella is the foremost authority on this, and his blog archives as Mises.org as well as C4SIF.org almost entirely focus on the subject of IP. You can find them in the links section at his Mises Wiki page, but here are a few highlights:
There are No Good Arguments for Intellectual Property
The Worst Argument for IP Ever?
Writers Can Prosper Without Intellectual Property (by Gennady Stolyarov II, actually)
Examples of Ways Content Creators Can Profit Without Intellectual Property
Funding for Creation and Innovation in an IP-Free World
Innovations that Thrive without IP
And of course there’s the other side of the argument as well…illustrated in pieces like these:
Yet Another Study Finds Patents Do Not Encourage Innovation
Germany and Its Industrial Rise: Due to No Copyright
How Intellectual Property Hampers the Free Market
If you can’t get someone to read a full book (like the first link in this post), perhaps give this a try: