quick update on my ubuntu experience ...
webex went fine. linux client seamlessly downloaded and allowed me to join a webex conference. joined the teleconference via skype with just a small hiccup - took me a couple minutes of tweaking with various sound levels to get my mac's built-in mic going. but iSight camera was working with Skype straight away, so that was nice.
but, near the start of my first full day, I needed to investigate an IE bug, so I tried booting up into my Windows partition. epic fail. blue screen immediately upon boot. :( tried fixing my mbr via the Windows XP install CD, but no luck with that either.
I remembered that the ubuntu instructions for triple-booting suggested installing GRUB on the partition with ubuntu, and I also remembered that I had missed that step. so, I decided to reset and start all over again. I booted into Mac OS (no probs there - in all of this experimentation I never once had a problem booting into Mac OS), and used disk utility to destroy both my ubuntu and windows partitions.
this time, I tried the other (easy) approach and after installing Windows, I ran ubuntu installer. this time I remembered to install GRUB on the ubuntu partition, rather than defaulting to the mbr. however, when I booted up again, I had the same experience - Mac and Ubuntu would start up fine, but Windows failed to start again. :(
because I constantly need to test in IE every day, I sadly decided that I needed to stop with all the experimentation and just resign to using Ubuntu on my secondary computers. :(
it's too bad - I would love to have a triple-booting MacBook Pro, especially if I could fire up both my Windows and my Ubuntu systems inside a parallels or fusion vm.