You won't get awesome FPS in Oblivion at 1600x1200 resolution and all features turned to maximum + HDR & quality 6xAA even with SLI 1900XTXs. Get a Core 2 Duo or the best AMD CPU and wait for DX10 cards.
Thanks, Pauldh. Your replies really helped me to clear my head. It is decided then. I will wait a bit and build the next gen rig. In the mean time I will be able to research new and upcoming hardware.