If you can - don't use PowerPoint at all. Lots of speakers use it as a crutch to keep attention off them and on the screen. I'm not brave enough to go without PowerPoint, but if you are a confident presenter try it without.

Otherwise, keep the PPT slides very basic. Also have a back-up and some handouts, at one conference the organisers lost my presentation (grrr) and I had to wing it without PPT. If you use PPT 2007, make a compatible version so it works on any system.

If you like to move about a room or stage, use one of those fancy wireless clickers to change your slides.

Ditto, I turned down Cambridge in favour of London.

IMO, at PhD level, it is more about the choice of your supervisor and unique specialism of the relevant department, rather than the reputation of the university as a whole. Your choice of supervisor and the availability of funding have to be the deciding factors.

UK Uni's for taxation:
University of London: LSE and Queen Mary
Cambridge and Oxford

As far as I'm aware not many other unis have tax staff.

You can do a one-year doctorate program in some European countries (eg Austria) where you gain the title of 'Dr'. However, some countries, such as the UK, do not recognise these doctorates as being of the calibre as PhDs, and some countries only place the 1 year doctorates as high as a Masters of Research. So beware...a one-year 'PhD' is not going to be worth much if you plan to work in countries who offer traditional (ball-breaking) PhDs.