For anyone having confidence issues, and doubts as to why they ever thought they could do a PhD i think it's all part of the process unfortunately - if you need further convincing, read "How to get a PhD - a book for students and supervisors" by Phillips and Pugh. It's frightening how they have summed up almost every thought i've had about myself and the PhD process - i could have written it it's that accurate! Needless to say i felt a bit better having read it:0)