My wife has a 1.0GHZ OS 10.2.8 512MB 17"fp superdirve IMAC it is about 3 years old and she has mistakenly deleted most of the files on her computer. So....now several things don't work and She asked me to reinstall OSX on it. We have moved twice(military) since we bought the computer and I have lost the DVD to reinstall it.
1. is it legal for me to borrow someonelses DVD to install on my MAC?

2. if it is, is there a product key or serial that I need off the Mac before I wipe it?Where would I find it?

3. If it is legal, and I get the serial number, is there anyone willing to let me borrow their disk? FTP it to me?

Thanks Johnno its not legalWhy isn't it legal?Because then you COPY that disk and that is piracy. If you don't believe me, READ the user agreement, I think it is mentioned in there...Copying a disk is considered a serious crime and you could spend some jail time and have a big fine.
If it were sent through a FTP, it would still be illegal because it is copied. (hence the piracy)
If anything, ask a neighbor for the same installation disk if they have it. Don't ask for a copy of the disk. In fact, thats probably not GOOD advice. Do all you can to avoid breaking the law. In fact, it could be an even better idea to search eBay. That's how I got my disk, new and still sealed in a package.If I own a license, and I borrow the same version of software that came with my computer, then it isn't illegalI CALLED APPLE ABOUT THIS THIS WEEKEND. that was for you blackberry
I am not trying to STEAL anything I am sorry that I live in a time were integrity is compromised by...anythingWell, I am sure we are all glad that you did the right thing and called Apple to find out. I can think of a bunch of people that would have just downloaded a newer version from Kazaa.
Just keep in mind, don't install a newer version, only install the version that you own a license to.  
Have a great day!