Rick Broida from PC world wrote a nice article about the trouble people have presenting their slides with their iPad’s. You can find the link to the full article at the bottom
He suggest installing slideshark which supports both ppt and pptx files. There are a few other apps which can read many of the MS office files we are all accustomed to using.
The most popular apps similar to this that I have used are keynote or goodreader both which have video out capabilities to connect to projectors or TV’s.
Another option is to use one of the more powerful pocket projectors that have on board file players. There are a few pico projectors that have the power to run ms office files directly from usb or sd cards and these include AAXA’s P4, along with 3m’s mpro series.