I was worried the I7 Imac wouldn't handle all the multitasking I was expecting, and it's passing with flying colors. From unzipping while copying another file while exporting IMovie clip while having Lightroom running, I never get the shiny color disk of lag I constantly get on my 2009 MacBook pro and my Mac Mini. Imac is totally silent, and all I hear are my external drives. This is really awesome. Had a budget of 4K, ended up spending 2K. I still have 2K to buy me a real good PC gaming computer with a top-gen videocard, and use the IMac as its screen. P.S. I still plan on eventually owning a Mac Pro, but I'll wait for the hum, 2012 refurbished units
If you're going to use the iMac as a screen, you'll need a DisplayPort capable graphics card. I'm not sure if there are any miniDisplayPort to DisplayPort cables, so you're safer going with a card that has a miniDisplayPort connector. Here is one: http://www.newegg.com/Product/Product.aspx?Item=N82E16814125303