Welcome.....
Briefly....
1. The DVD "Restore" set that came wiht your purchase of the Z600 from HP is what you need..... go find those, and read up on the Restore process. This is your very best option. Many people amazingly throw those away or lose them.
2. HP usually provided a backup as a Restore partition on your original drive from the factory..... you can make a single copy of your Restore media from that partition. I would use a 8GB quality USB stick for that.
3. HP does not have any more originals from that far back. That will not be an option in my experience.
4. Find a set from a friend who has a same type (version 1 vs version 2) Z600 and restore from that set. There is info in this forum on how to tell from your Boot Block date in BIOS what version you have. You want one with SP1 built in. Virtually all available now will have that.
5. Buy a new Windows 7 Pro 64-bit system builder license and media from Amazon and do a clean install from that, however see 6 below before doing that.
6. If your Z600 has a W7Pro64 COA sticker on its case (look on the bottom too) with a legible COA serial number borrow a Windows 7 Pro 64 system builder DVD and do a clean install from that media, using that COA serial number, and add drivers as needed from the HP Z600 drivers site.
