From this guy’s Flickr
The MacBook Air is finding its way into wanting hands and some early benchmarks have been tallied. There’s two main differences between the two default MacBook Airs you can buy—a 1.6GHz vs. 1.8GHz processor and an 80GB hard drive vs. a 64GB solid state drive. The price difference may be $999; it’s up to you whether or not the following differences are worth that to you.
CPU performance in the 1.8GHz model is marginally better than the 1.6GHz. I doubt you expected 200MHz to matter much, anyway. But it’s the hard drive vs. solid state comparison that people were most interested in.
Sequential file writing—loading big files into RAM—is a slightly slower affair with the solid state drive. Non-sequential writing, on the other hand, is a different story.
In non-sequential writing, a hard drive would be spinning all over the place, trying to locate spread-about files all over the different platters. Not so in a solid state drive. Thanks to the lack of moving parts, the solid state drive is noticeably faster. This here graph shows the actual numbers.
So there you have it.
MacBook Air 1.6Ghz HDD vs 1.8Ghz SSD Benchmarks [MacRumors]