My son is eagerly waiting to buy the new Spore game, but needs a better graphics card than the stock Intel 82845G/Gl/GE/PE/GV (reading off control panel info) controller that our Dimension 2400 desktop came with.  We bought a Stealth ATI Radeon X300 SE that is PCI Express compatible, but after opening my tower, it doesn't look like it will fit.  Any suggestions for other ATI products?  We have XP, Intel Pentium 4 2.66 Hz chip.  Thank you!