Hi Ros,
Here are the system requirements for upgrading to Snow Leopard:
- Mac computer with an Intel processor
- 1GB of memory
- 5GB of available disk space
- DVD drive for installation
- Some features require a compatible Internet service provider; fees may apply.
requires an additional hard drive or Time Capsule (sold separately).
requires an iSight camera (built in or external), USB video class (UVC) camera, or FireWire DV camcorder. Backdrop effects when using a DV camcorder require fixed focus, exposure, and white balance.
requires Windows XP with Service Pack 2 or Windows Vista (sold separately).
in iChat and the Finder requires a 128-Kbps Internet connection (300 Kbps recommended).
requires a 1.6GHz processor or faster for improved deinterlacing.
- Audio chats require a microphone and a 56-Kbps Internet connection.
- Video chats require an iSight camera (built in or external), USB video class (UVC) camera, or FireWire DV camcorder; and a 128-Kbps upstream and downstream Internet connection.
- Backdrop effects when using a DV camcorder require fixed focus, exposure, and white balance.
- Some iChat features offer better performance and quality with higher system capabilities. More details
requires Microsoft Exchange Server 2007 Service Pack 1 Update Rollup 4. Auto-setup requires enabling the Autodiscovery feature of Microsoft Exchange Server.
requires iSight camera (built-in or external), USB video class (UVC) camera, or FireWire DV camcorder.
requires a Mac with an NVIDIA 9400M graphics processor.
require 1GB of memory and an additional 3GB of available disk space.
requires one of the following graphics cards or graphics processors:
- NVIDIA GeForce 9400M, GeForce 9600M GT, GeForce 8600M GT, GeForce GT 120, GeForce GT 130, GeForce GTX 285, GeForce 8800 GT, GeForce 8800 GS, Quadro FX 4800, Quadro FX5600
- ATI Radeon 4850, Radeon 4870
requires a Mac with a 64-bit processor.
requires a Mac with a multicore processor.
If you have an Intel processor, and enough free memory, then you should be able to install Snow Leopard. It's possible that the disks your friend gave you are machine-specific, and that is why they would not load on your Mac. If you purchase your own copies (and, again, have made sure that your computer meets all of the requirements), then you should have no issues loading the one you purchase. Once you have Snow Leopard installed, you can purchase Mountain Lion online and download it to do the upgrade.
Hope this helps!
Cheers,
GB