Ubuntu eating my disk

[ROBERT@hsp:~] df /dev/sda2
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda2             46442536  33489000  10594392  76% /
[ROBERT@hsp:~] echo "(46442536 - 33489000 - 10594392)/1024" | bc
2303
[ROBERT@hsp:~]

Where are my two gibibytes of missing disk space?

I don't want to start a holy war here, but what is the deal with you Unbuntu fanatics? I've been sitting here at my freelance gig in front of a PC (a Dell Inspiron 1420 w/4 GB of RAM) for about 20 minutes now while it attempts to copy a 1.7 GB file from one folder on the hard drive to another folder. 20 minutes. At home, on my Mac Pro running 10.5.6, which by all standards should be a lot more expensive than this Dell, the same operation would take about 2 minutes. If that.

In addition, during this file transfer, Opera will not work. And everything else has ground to a halt. Even GEdit is straining to keep up as I type this.

I won't bore you with the laundry list of other problems that I've encountered while working on various Linuxen, but suffice it to say there have been many, not the least of which is I've never seen an Ubuntu install that has run faster than its OS X counterpart, despite Linux's open-source architecture. My Mac mini with 256 megs of ram runs faster than this dual-core machine at times. From a productivity standpoint, I don't get how people can claim that Linux is a superior OS.

Linux addicts, flame me if you'd like, but I'd rather hear some intelligent reasons why anyone would choose to use a Linux over the faster, more expensive, more stable system.