SMB Windows Share - Intermitant Dropout

Wondered if anyone can help?

I've recently got my first iMac and love it however am having problems with networking it to my Windows Vista Ultimate machine. The shares on the Vista computer are fully shared so the iMac has read/write access. I have also created a script (volume mount), saved it as an application and saved this in my logon items.

The problem is maintaining a consistent network connection. On my desktop I can see the shares and access them, I can read and write but when I try and transfer large amounts of data at some point it springs up an error saying 'one of the files could either not read or write'. There is no particular file this error relates to as I can restart the file copy and it will get past the issue but then spring it up later on.

Also have problems when using iTunes with music stored on my Vista computer due to the same issue.

Any help would be great!