The bottom line is that there is no wrong choice. What it comes down to is the future of the hardware and the users overall impression with the particular hardware. ATI's Catalyst drivers have proven to be fast, stable and easily configurable. Using ATI cards for the last few generations the drivers have grown on me and I haven't had a stability issue with them in along time. The X800 core is dates back to the 9700 Pro with revisions and updated features added however the drivers have matured fully and gaming compatability is top notch across the board. The X800 series only supports up to Shader Model 2.0b, but ATI adds support for their own 3Dc compression technology. The X800 Pro only has 12 Pixel Pipelines and in the future this may hinder the performance it's able to deliver. The Sapphire X800 Pro was faster in many Direct X 9.0 applications and older games, it's power demands are less but the card generated more ambient heat in the case.

Pros - eVGA 6800 GT
- Fast.
- Supports next generation features (UltraShadow II, SM3.0, etc).
- Single slot, single power connection when compared to 6800 Ultra series.
- Improved Anisotrophic Filtering when compared to X800 Pro.

Cons - eVGA 6800 GT
- Louder than X800 Pro.
- Requires a dedicated single chain from PSU for optimal power supply.
- Performance in older games when compared to X800 Pro.
- Performance with AA/AF enabled when compared to X800 Pro.

Pros - Sapphire X800 Pro
- Fast.
- Quieter than 6800 GT.
- Single slot, single power connection.
- Support for 3Dc Compression Technology.
- Less demanding power needs.
- Improved Anti-Aliasing quality when compared to 6800 GT.
- Performance in older games, compatibility with older games.
- Faster than 6800 GT in many applications with AA/AF enabled.

Cons - Sapphire X800 Pro
- Only supports SM2.0b, lacks support for future features.
- Slower in OpenGL applications than 6800 GT.
- May use additional bilinear and trilinear optimizations lowering IQ.