Some Linux flavours are very light on resources. I am, for instance, typing this on an old laptop (my very first PC) which started life with 128MB of RAM, since upgraded to 384MB, currently running Bodhi Linux on its 20 gig hard drive.

It functions fine as a net browser and e-mailer by my bedside. Video is a bit jerky and not full-screen for newscasts and u-tubes, but the sound is smooth enough. The machine described by JiK above could run a number of different versions of Linux.

I have tried a few of the dozens (probably hundreds) of Linuxes available (you can even compile your own version if you get crazy about it) and found them a very mixed bag, particularly as regards ease of installation. Some established products from large teams of developers are very slick, others much less so. As a non-techie type of person I am not the target-user for a number of the systems, and I have found myself completely baffled by some that claim a low operator-skill requirement.

You need to be prepared to break things a few times and start again, but Linux is definitely worth a go. A separate partition is essential, a separate drive or machine better. I have found distrowatch a good place to start from.