Hi,
As someone else has said, acceleration off the line is hampered in a diesel, probably because the red-line rpm of around 4,500 (and really only to 4,000rpm is worth it) gets used up real quick and not even the bags of torque that diesels have makes much difference. By 2nd, certainly 3rd gear though, they pull really hard and go very well.
I changed from the 1.6 16v Polo GTi (125bhp) to a 1.9 TDi (105 bhp) and I really didn't notice all that much difference in performance - the diesel drives quite differently, and once you realise that, all the overtaking is just as swift
Leon.