[psgbg]

You can download a netiso (net install / minimal iso). That kind of ISOs are between 80-250 MB (or even less) and contains a base system only but you can download the "rest" of the system from internet.

https://help.ubuntu.com/community/Installation/MinimalCD http://www.debian.org/CD/netinst/

But If you are not confident enough with Linux perhaps you might consider other options.