inconsistant user name in data easy transferring

Hi,
I have done a data transfer from my old PC running XP to new laptop running
Vista. Unfortunately I didn't reliase the user name in old PC is different
to new laptop I created but with same password. Now I can't even login to
laptop due to incorrect user name.
I correct old PC's user name to match with new laptop, however because I
can't login, I can't even make network working again which made me unable to
re-do data transfer.
What should I do? HELP !!!