Please do this the right way. Any issue concerning IP and claims of infringement or violation of rights requires due diligence on both sides. At a very minimum, you should read the transcript of Andrew Tridgell's talk on patent defense at http://news.swpat.org/2010/03/transcript-tridgell-patents.
That your software is open-source is entirely orthogonal to the issue of infringement.
That your software is open-source is entirely orthogonal to the issue of infringement.