Trade it in for a PC with a good video card.
Just joking, but I am scared that the video card(s) will be a disappointment.
Video editing of many different kinds. (FCP, Combustion, Compressor etc)
Edit and Make DVDs. (MacTheRipper, DVD2oneZ, Toast 8, DVD SP, Cinematize etc)
iPod, iTunes downloading.
Maybe screw around with Windows.
GTD type organizing
Porn (just joking, maybe not, well maybe, no won't do it, well...)
More computing! I don't care at all about the debates over graphics cards (I bought three of the simple GeForce 7300 cards), but I love the speed at which I can compute with my MacPro. See my signature. It's great.