How often do you back-up your files?

Most of the files are opened other than the C drive and hence I do not take any back up of any files. The files are not important for me since I do most of the files for my clients and it is stored either in the CDs which they bring or pendrives.

i am so busy that i hardly have time to organize, much more to back up files. but i also did that once. i made a total of 5 cds as backups. hehe now, i bought six, and hopefully i can reorganize things and back them up...and maybe delete them so i can have more disk space. my virtual memory gets too low sometimes. I already bought cds to save the stuff that I have, but i still don't have the time to organize them...hehehe time, i need more time. hehe i am also thinking of getting that external hard drive. but do you think it is better than having them on cds and dvds? what do you think will last longer? is there a fool proof method of saving digital data?

mmm... not too often, I mean, I backup them on a CD maybe once a year, but I am doing now it is to put them on my email, that way I have them anywhere I go...