While I am somewhat unfamiliar with the programs you listed (I have used them, but as my field is network design, not extensively), I have to say that my vote - at this point - may well be for the Macintosh computer.
I don't say this because of the usual "Mac Zealot" kind of thing, but because the ease of use and current lack of offensive software (Offensive as in, offensive weaponry) that is rampant for OS X would probably lead to a much less frustrating work environment.
The switch to Intel is largely irrelevant at this point, if you're looking to buy a computer. While the starry-eyed will proclaim that we'll see a Yonah Powerbook by May next, I personally find this extremely unlikely. Moreover, Apple - certainly not alone as a hardware vendor - has a lot of issues with Revision A hardware, which is why I would personally advise caution. The current PowerPC-based Powerbook line is, if I recall, in Revision D - it is now a stable, mature platform that is highly reliable. Additionally, software will be available for both Intel and PowerPC platforms for years to come - this from The Steve's own keynote, so I feel it's a pretty good thing to believe.
It seems that many journalists and graphic designers also favour Macintosh computers over their PC counterparts - not being in the industry I am somewhat unsure as to why, but it seems it must be a fairly ironclad reason.
Powerbooks are much more expensive, yes - but I believe that their overall quality in terms of software, support, and actual physical build quality - is more than worth it. Powerbooks also come with a bevy of additional little extras that just make it a nicer computer to play with - the Ambient Light Sensor system is oddly compelling, once you get to play with it. While I won't say anything bad about an 1100-dollar Toshiba, I believe that the Apple machine would outshine it in several areas.
Your mileage will, of course, vary. My advice would be to skip the Toshiba and pick up a Powerbook (or iMac, depending on how much your computer will travel - the iMacs are much more Computer Per Dollar), which should last you for a significant period of time - there are many TiBook owners who have machines dating back to the 500-800MHz era that claim Tiger runs perfectly on their machines. I personally have a G3 iBook at 333MHz that seems to run Panther 10.3.9 with a remarkable aplomb, so I would not expect a Powerbook of the current generation to become obsolete in the near future.