Turn on anistropic filtering to 4x and see what you get. I'm curious to see the results. When I had a Ti 4200 overclocked to 4600 speeds turning on AF completely killed my framerate. (Just a note: AF doesn't work right on nVidia cards with some 40 series drivers. The 43.65s are an example.) If it works right 4x AF should really allow you to see more detail in the terrain. Unfortunately it's hard to see the difference on my screenshot, because the compression scheme JPEG uses has the effect of blurring textures.
Regardless, getting 75 FPS with a Ti 4600 with 4x AA turned on at 1280x1024 is excellent.
BTW: Prescott support on current socket 478 boards is by no means a certainty. The early power consumption estimates Intel released by which the MB manufacturers based Prescott compatibility on were revised a couple months ago and were revised again just a week ago or so. As far as I know, only the Asus P4P800-E is capable of meeting the revised specs. In addition because of the delay in Prescott's release schedule, it's unlikely Intel will release more than one or two Prescott cored P4s in socket 478. Intel is currently showing LGA socket 775 using the Grantsdale chipset for Prescott's projected 2.8 to 3.6 GHz currently scheduled Q2 2004 release on their newest roadmap. Given the latest delay in Prescott's socket 478 release to mid-Q1 2004, that doesn't give them much time to release more than 1 or 2 speed grades. Even the latest revision to the power specs would only allow for around a 3.4 GHz model to fall within the P4P800-Es maximum current specs. I hope Intel finds a way to get power consumption down a lot, or quite a few people who bought Springdale and Canterwood socket 478 boards recently are going to be angry or at the very least disapointed that their boards are not going to be compatible with Prescott. (Myself included, I've built a few P4P800 systems now.)