All you have to do is open up Addressbook and type in the search box what Vcard you are looking for, if it's not there or you need to restore the whole Addressbook just run Time Machine and make sure that Addressbook is the active window and that's it.
. . . I goto time machine with the contact open in address book... and no matter how far i traverse back, the hospital number is the most recent one and doesn't change to the one i had on there a couple days prior.... as a matter of fact, the hospital number is STILL on the contact card even if i traverse back a month..
If the display is "frozen," showing the same thing in all backups as the "Now" page, it's a known problem on Snow Leopard. See #E5 in http://web.me.com/pondini/Time_Machine/Troubleshooting.html
Your Address Book info is stored in /Users/<yourusername>/Library/"Application Support"/"Address Book"
To back it up, back up that folder. To restore, put the back up of that folder in place.
Time Machine should be backing it up automatically anyway...