So, Nancy, have you made it back to Earth yet?
I would say figure out what *exactly* you need the laptop for first (as suggested by a couple others). Realize that there are significant compromises involved between power/performance, usability/ergonomics, feature set, upgradability, size/heft/portability, battery life, $$$, backwards compatibility w/ what you already own, etc.
If $$$ and backwards compatibility are not issues, then that would make the decision much less difficult, but still not exactly easy.
Regarding deciding between Mac vs Wintel, go try out a Mac (or Powerbook) at your local superstore in person to see. If you fall in love w/ the Mac (or Powerbook) right away, then you probably have your answer. That's assuming $$$ and backwards compatibility are not issues for you (since you already own an old PC?). The Apple solution tends to be higher $$$ out-of-the-box, BUT it does usually come w/ more/better software and integration, which you can determine (to a good degree) for yourself by playing w/ one at a superstore. However, you should note that Nikon software runs much slower on Macs than on Wintel PCs, and while most software available to Macs may be of higher quality, there are also far fewer to choose from, so it's possible that a power user may miss out on something on the Mac side -- and the reverse can be true as well. And also, in the long term, you can probably expect most new significant software to be developed first for Wintel before Mac. OTOH, bleeding edge software/technology has its cons too.
For me, I would liken Mac vs Wintel to Nikon vs Canon to some extent.
FYI, I'm primarily a Wintel user -- haven't used a Mac in a very long time -- but mostly because of the $$$ factor in addition to my work (as a programmer). I have no particular love for Wintel and can hate Microsoft stuff (and its spawn) as much as the next guy/gal anyday of the week -- and don't ask me about .NET.
I'm also a parttime Unix user too (for work), and would probably love to switch (back) to Mac one of these days since it uses Unix core now, if my work no longer involves Microsoft stuff, which is not likely in the forseeable future. Actually, there are a few web designers here that use both Mac and Wintel for their work -- and they sometimes forget to make the proper translations for the web designs.
So anyway, decide what you really need first. And go try out a Mac for yourself to see if you want to switch. For some, it will be like picking up a Nikon body for the very first time and feeling that it's somehow perfectly suited to you while the old Canon body just never was this comfortable and easy to use. OTOH, there could be some great features or options practically exclusive to the Wintel side that you might miss if you switch -- in Nikon vs Canon world, Canon has more IS and USM tele lenses and also the option of full-frame sensor format for instance.
_Man_
