I ordered a new iMac 2.0 ghz processor and 1 gb of ram, dvd burner and a 160 gb hard drive. The only problem is that under about this mac it says my hard drives mac capacity is 149.05 gb so i order 160 how come it is not 160 gb???
We humans tend to base capacities off of 10, but a computer bases it off of 2, hence the 256, 512, 1024, etc. If you want to find the actual capacity of the drive, divide the number of bytes (160,000,000,000 for you) by 1024 3 times... then you will know the actual capacity. Besides, who wants to read long decimals and odd numbers, don't we want a regular number?
I'd just like to add that every hard drive (or other storage device) manufacturer does this. You can't buy a 160 GB hard drive and have it show up as 160 GB.
Think of it as advertised gas mileage with cars. What's on the sticker assumes ideal conditions. It's not quite the same thing with storage capacity, but they get away with it for the same reasons - you can compare different models relatively (200 GB is twice the storage of 100 GB by any measure) and it really doesn't matter that much to the average consumer.
A 15" MacBook Pro doesn't have a 15" screen either - it's 15.4". Apple reports it as being smaller for the sake of simplicity.