Actually it's 3.5GB/.5GB, not 3/1, so the odds of you needing more than 3.5 but less than 4 (at which point it will slow down anyway) is fairly slim. Still, performance at 3.75 is better than at 4.25, it's a middle ground.
They could've easily just sold them as 3.5GB cards but it would've taken marketing effort to explain that to the uninitiated and that extra .5 as I mentioned does offer a benefit over being forced out to main RAM.
The Jedi Master
The anteater is wearing the bagel because he's a reindeer princess. -- my 4 yr old daughter
