I upgraded my Cube about a year ago from a 450 MHz CPU and the old ATI 128 Rage Pro video card to the following: CPU: 1.5GHz: http://eshop.macsales.com/item/PowerLogix/PF47S1500CN/ . Comes with a fan (it is quiet), which is important since the video and CPU upgrades together throw off more heat than the components they replace. Video Cards (and brackets): http://www.yourmacstore.com/shop/shopdisplayproducts.asp?id=241&cat=AGP+Vide o+for+Cube . I opted for the Radeon 7500 32MB card, with neither heat sink nor fan, and had to buy the assembly brackets separately at http://www.yourmacstore.com/shop/shopexd.asp?id=173 . The upgrades work fine. No problems with overheating or performance and I use the Cube daily. I am running OS X 10.4.11. I upgraded the Cube¹s memory from 500 MB to 1.5 GB. I also upgraded the optical and hard drives to really pimp it out. Good luck. Eddie