a "backup" is only a backup if it's a full copy and not in the same place as your computer. I recommend mozy online backup, but if you need to get it done right now, you don't have time for that because the initial backup takes a while.
Your other option is backup software that will compress your files and burn them to CD or DVD (whatever your burner is)
But frankly, yes, you should suck it up and eat ramen for a week or two and get one of these:
http://www.overstock.com/Electronics/We ... oduct.htmlThat's what I have with me pretty much all the time for my photo shoots, or did until I got my one with the card reader built in. They are quite durable, and for under $50 you can't beat 320 gb of space, and they don't need an external power source.
It's not a great
long term solution, but it's good for short term, and good to have around.