Where are you getting a faster benchmark from? There's a common task shared between those two benchmark readouts -- "Windows Media Encode"; they apparently don't give any detail as to exactly
what they're encoding, so there's no way to judge whether they're doing high-framerate hi-res content, or something else. The MacBook finishes the job in 8:07, while the fastest of the XP-benchmarked finished the same job in 7:37 -- thirty seconds less.
If you're only going by the speed ratings (2GHz on the Acer versus 2.16GHz on the MacBook), there's a lot more to it then that.
Another off-putting point is that Apple most likely isn't going to publish Windows drivers for their hardware, which means, in short, no acceleration. This is a drawback for applications like Adobe Premiere and games like Doom 3, all of which use Direct3D coupled with the system video card to accelerate video. Occasionally you'll see an application that uses hardware-accelerated sound (DirectSound) as well.
(Ironically to note, the compared
Polywell box, a high performance desktop, finished the job in 7:47, while the Asus TravelMate 8204WLMi! finished in ten seconds less and is a laptop!)
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.1) Gecko/20060130 Donzilla/1.1PR1 (WML/1.3)
Laptop: HP Compaq nx6325 - Turion 64 X2 @ 2GHz, 2GB DDR2, 100GB HD, ATI Radeon X300, 15" LCD, Seven Pro
Handheld: Palm Treo 650 - Intel PXA270 @ 312MHz, 10MB RAM, 32MB flash, 2.7" LCD, Palm OS 5.4
