First off:
DDR2? Are you going Intel? As of right now, the A64 is the superior gaming chip. The P4 is better for video encoding.
Second off, avoid Sapphire AT ALL COSTS. Get the Gigabyte X800 Pro. It's much faster than the 6800 non-GT and is an assload more reliable than Sapphire crap.
My Sapphire 9700 Pro HAS BAD RAM. On top of that, the contruction is shoddy, i.e. non-reference ATi design that is more prone to problems. The circuit designs are worse, and coupled with the shit-ass EtronTech "2.8ns" memory, it's 5% slower than a real ATi board with 3.3ns Samsung RAM.
ATi also has better Windows drivers, but for Linux nVidia is the only option.
For reliable DDR2 RAM, get Corsair, Crucial, Mushkin, or Samsung. Corsair is the best out of all those.
Infineon is good too. My main rig has 512MB Infineon PC3200 RAM in dual-channel and it's very reliable. I bought it from a friend for $50.