While the history of some NPC groups regarding integration has been storied, things have changed and are changing. There are quite a few African Americans on GreekChat who are members of NPC sororities and NIC/IFC fraternities, as well as multi-cultural GLOs.
Also, as sigmadiva said, you really need to think about what you want out of sorority life. If you want to be in the more "social" aspect of things, go NPC. If you want to join a more service oriented sorority, then NPHC might be more your speed. That's not to say that NPC groups don't do service, and NPHC groups don't party and have a good time, but the two systems are vastly different.
I think that openness to your pursuit might also depend on your geographic area, but I say GO FOR IT. You never know until you try, and who knows? If you find yourself more comfortable among women who are members of NPC sororities, then by all means, choose where your heart leads you.
Good luck!
PS - I sent you a private message!