iMAC Problems!!!!

My computer is giving me fits! I want to shoot it right now!! I have a 24" iMAC that I bought in January; and it just quits on me in the middle of anything I'm doing. My husband determined tonight it it not Snow Leopard. He thinks it's hardware related and probably in the graphics card. It's been quite an evening of attempting to get the holiday card image ready to go to the printer, Modern Postcard, tomorrow. Needless to say, I'm going to bed with the card unfinished. I'll just have to stay late tomorrow and get it done. Wish me luck...I'm about ready to tear my hair out!!! TTFN sdg