The new Mac's are susposed to be very nice and seem to have come down in price. IMHO their biggest advantage is that they present a smaller target for virus writers and they do very nice graphics.
That said, is there a particular application that only the Mac can run? You can go TOP end with a Windows / Intel box and not break $2000. For example, check out this Dell page:
http://www1.us.dell.com/content/products/features.aspx/outrageous_desktops_beta?c=us&cs=04&l=en&s=bsd
If you do go Mac again, make sure you get the new Tiger OS. HTH