What is the best way for me to back up my pc.?

Hi , I recently did that horrible thing everyone tends to do, I was using the net, I got a virus, and my computer was broken… No backups. I booted to a linux live cd and managed to backup all my necessary files. But the os was another matter.
I tried the acer recovery on windows (which is an acer aspire one net-book) Basically it tries to overwrite c with another partition, stored on the drive. But it refused. I got a bit worried here, thinking the virus got at the partition, or maybe it got corrupt from movement or something. Anyway long story short I found that there was a start up option to a restore program that did not require windows and I got my system back to manufactures settings.
To ease my mind of this happening again I contacted acer, to inquire about some cd’s to back up from in case of future corruptions to the hard drive.
Well I got a reply stating they can re-image the drive for free while under warranty, or to my shock they can send me the cd’s for around £50.
Now I’m not being cheap but £50 is just a disgrace, if AOL can send me 30 cd’s trying to get me onto their service, for free with no postage, then why is a company I already funded charging £50 (and since the only re-image during warranty, it seems like an extra, hidden charge.)
Well obviously I declined the offer, but that leaves the problem of how to backup the partition, any ideas?
Thank you all in advance