I looked into this as well a few days about because I absolutely hated my text messages showing up as convo's, very confusing. While the registry edit does indeed fix the convo view/threaded sms issue, it also prevents you from receiving a notification when you receive a text message, at least it did for me and several others. The link below however will install a small program that fixes the threaded sms while disturbing nothing else on the phone...
http://forum.xda-developers.com/show...1&postcount=31