I use IE on Windows when I'm on wireless on my notebook - its my primary personal pc and it dual boots (XP Pro and Debian).
My work involves the use of VC++ and is for the Windows platform, so during that time I'm on IE/Mozilla (depending on what I do).
When its school stuff, the programming is mostly done in either C, Java or Perl, and so I prefer Linux.
If its personal stuff, it really depends on what is it that I want to do. Quite honestly, I would spend about 60% of my time on Windows and about 35% on Linux. I'm really uncomfortable with Macs (use them because I have to - and only commandline plus matlab)
and they perhaps contribute to 5% of my use.