I also recall the ruined CD thread.
The problem with printing your pics and erasing the card is you lose the original files. That means you can't go back later and crop, edit, reprint, etc.
For the pretty low cost, I think it makes more sense to buy another card. Chances are it will come in handy again in the future. I've got 2 256MB cards which gets me over 500 shots and I'm planning to buy another before our cruise in March. I'm just waiting as long as I can because the prices continue to drift down. By then, I'll probably be able to get a 512MB card for about $50.