I think your best bet is to get an external HDD (same size or bigger than the drive you will be backing up) and then image your HDD with something like Acronis True Image or Norton Ghost. I myself use Acronis True Image. As long as you make a backup at least once a month you should keep on top of your data. I myself don?t keep my back up drive plugged in, but this is only so I don?t format the drive by accident (because ive done that before) and so it doesn?t get unnecessary usage and over heating.
There was a recent poll on CNET about this:
http://forums.cnet.com/5208-7810_102-0.html?forumID=77&threadID=241717
how should i back up my xp machine? i have about a 80gb hard drive with two 40gb partitions. recomend software. why would i need to back up OS?
pics are most impor|ant. im planing on an external HDD. should i leave the HDD pulgged in after back up? im worried if i do that that it could just get infected Just like the rest of my P.C.?i would use DVDs but i dont have a DVD burner and this seems cheaper in the long run because there is no blank media required.your help is appreciated.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic