The NVIDIA is quite a bit better than the Mac Mini graphics card. Don't expect too much from the Mac Mini's graphics card. Whether you will notice a difference or not really depends on what you're planning on doing with it. As far as day-to-day web/office/email use you won't notice anything at all. Especially because OS X performs quite bit better than Vista as far as resources go (and other things, too...). Don't expect any 3D games to run very well, though. If you do Photoshop-type stuff, you may notice that to be slower, but it'll be adequate. If you're a heavy Photoshop user or work a lot with editing video you may want to go for an iMac instead. Beyond things like that, you won't notice too big a difference. Especially as far as normal, every day performance goes.