The only three differences between the two models (very little differences) are the following:
1. The clip on the remote control; the 760 has a spring mechanism to clip onto your clothes while the 710 is a static clip (like on a pen cap).
2. The flip screen cover on the 710 is purplish; the one on the 760 is silverish.
3. The OS on the 760 has been upgraded (you can do this on your own or pay Sony for peace of mind since it's like flashing a bios; once it's flashed successfully, everything will be fine) to 4.1 instead of 3.5.2. You can download all the upgraded software for the upgraded 710 (in other words, get the software that comes with the 760) from Sony's web site.
OS 4.1 makes it much easier to connect to Windows XP, and I believe the OS supports more color displayed on the screen than OS 3.5.2 (256 vs 16-bit); USB connection is also supposedly slower on OS 3.5.2 for Clie because it is simply an emulated serial port (so I have been told; Handspring is the one that innovated the USB connectivity concept). If you have the capability to do the upgrade yourself, it's probably better to just get a 710; same identical ELECTRONIC hardware.
You can't go wrong with either, they're great PDA's; by far the best Palm-based PDA's on the market, and the best resolution for this kind of products (320 by 320; you get beautiful sharp pictures you can carry anywhere). The only thing the Clie doesn't do too well yet, and we know it has the ability because there are tricks (a bit inconvenient), is to play good videos. Someone like Teal ought to take advantage of that great sound chip the Clie is gifted! I read somewhere of a way to manually sync a video stream from Teal, and playback the audio in mp3 format via the audio player (must sync voice and video manually). So you can get 25fps at 160x120 video (256 colors though) with 128kbps mp3 audio. gMovies can handle about 16fps on 16-bit color.