vista has lots of problems with copying files...
they say that this issue will be fixed with service pack 1
You can try disabling your antivirus , and see if its better...
There is also a program that will help you ...
see here
http://www.codesector.com/teracopy.asp
TeraCopy is a compact program designed to copy and move files at the maximum
possible speed, also providing you with a lot of features:
Copy files faster. TeraCopy uses dynamically adjusted buffers to reduce seek
times. Asynchronous copy speeds up file transfer between two physical hard
drives.
Pause and resume file transfers. Pause copy process at any time to free up
system resources and continue with a single click.
Error recovery. In case of copy error, TeraCopy will try several times and
in the worse case just skips the file, not terminating the entire transfer.
Interactive file list. TeraCopy shows failed file transfers and lets you fix
the problem and recopy only problem files.
Shell integration. TeraCopy can completely replace Explorer copy and move
functions, allowing you work with files as usual.
» Download TeraCopy - Free for Home Users