In reply to Orcan and Fernando and the rt kernel issues in F15, I have used the ck(Con Kolivas) patch and had good results while using JACK on Fedora 15. It is fairly straightforward to patch and configure. I won't say that it is better than the rt kernel because I never tested enough to know for sure. The only drawback is that this patch is not officially supported by the linux community. It is only a side project that he does for "fun". Anyways, it may be a temporary fix until the other problems with the rt kernel are sorted out.
Thanks everyone,
Bill Blackburn