There are many places on-line to download Windows Vista but
most of them are illegal. Windows Vista is distributed on-line but only from from
Microsoft.
If this is a
Dell, or other branded system, contact them for a set of recovery disks.
There is nothing wrong, however, in borrowing a Vista DVD off a friend, just make sure you use your Key, you need a valid Vista product key to install and use Windows, and use Vista Home DVD for a Vista Home install.
note: any spammers linking to any other site except Microsoft will find me quick on the ban button.