Ypu may get more expert help in the Networking Forum on this site but let me see if we can make sense of what you are saying.
1. You have a desktop (PC)
2. You have a Laptop for Work (laptopwork)
3. You have a Laptop for Home (laptophome)
4. These are connected on a network - is it a wireless network?)
5. Laptophome has Win7 and can connect to the PC which is on Vista (is this a two way connection ie you can both send and receive files from the PC to laptophome and vice versa?)
6. Laptopwork is on Vista and if you try to pass files from the PC to it you get asked for a password that you don't have. (question - does this also happen if you try and move files from laptophome to laptopwork?)
Have you enabled file sharing on laptopwork? Have you entered the Security Code (WEP or WAP)?
These are just my random thoughts in trying to understand your setup and bump you back to the top of the list.