I must admit there are quite a few programs that I need to use a PC, so I have Virtual PC running all the time. Hopefully that number will become less and less. I mainly use my computer for Internet, photo, video, itunes and email so the Mac works very well for that.
I also have my vehicle workshop manual which is in loads of pdf files. Typing in a word to search for and having spotlight return the results within 1 or 2 seconds is amazing, a PC would take minutes to do the same thing.
I do still have my work notebook so I still have access to a PC if needed.