and, as the thread suggests, was wondering what would be the 'best' the board can handle. As it's the original PCI-E and not the newer revision, something like an Nvidia 480GTX would probably be a bit of a waste, though I am planning on upgrading the CPU and RAM as well, so no worries about bottlenecking. Cheers!
More aboutwhat card asus deluxe take
No worries, even the most powerful current GPUs will have plenty of bandwidth on a PCIe 1.x 16x slot. Currently the 'best' GPU you can get is the GTX 580, although you would probably be better served with a much less expensive GTX 570 or 6970.
Just be sure to check that your PSU has enough amperage before dropping a monster card into your rig!