Vi or Emacs
Definitely vi here. I've been a user of Vim for nearly 6 years, and I couldn't be happier. Before that, I've used Xemacs for almost a year, but could not stand the kitchen sink when I just want to quickly edit a file.
Mac or Windows
Currently I'll say Mac, especially with Mac OS X, because of the un*x core it has. I can't really say that I'm fully switched as I still spent majority of time in front of a Windows computer at work. There are also things that I can't get used to in Mac. But I am hoping the up-coming Panther would be better.
IE or Mozilla
Mozilla for sure. The only reason that I am still using Internet Explorer is that our product at work only works with IE... :( When I am on a Mac, I'll probably use Safari.
Linux or FreeBSD
Despite my few attempts to play around with FreeBSD, I still favour Linux, because I am already familiar with the platform. Well, I heard many report that FreeBSD is supposed to be better as single processor networking servers, but I think my time is better spent on something else than master 2 un*x-like platforms. So for this one, I'll say Linux.
Bash or Tcsh
Definitely bash. Nothing to do with GNU, but it just happens to be the shell I'm used to since I started using Linux. With the un*x accounts I have, the first thing is usually chsh -s '/usr/local/bin/bash'
Perl or Python
If you have been reading my blog, you shall know that Python rules. My Python experience is nearly 3 years, and prior to that I have around 4-5 years of Perl experience. But I just felt that I am so much more productive with Python.
KDE or Gnome
I'll say KDE. I first encountered KDE back in '97, and I have never really seriously used Gnome. But then again, I have not used Linux as a desktop system for a while...
MySQL or PostgreSQL
MySQL for now. Even though someone might argue whether MySQL can be qualified as a real database system, but it is easy to develop, is used by many Open Source projects, and are deployed by most web hosts. Last time I used PostgreSQL was in the 6.3-6.5 days, and lots of troubles (database corruption, slow performance) back then. I heard it is much better now.
x86 or PowerPC
I love Mac OS X. I love Apple hardwares. However I wish PowerPC can have a much better price/performance ratio. I think I'll pick x86 here.
IDE or SCSI
IDE, again for the price/performance reason. I've never owned a SCSI equipment, but my experience with these drives at work, they don't give you 2-3 times the performance in every day applications.
Hopefully this entry won't be flooded with comments from FreeBSD Gnome users posting with Emacs :)