Fractured YEARFRAC and Discounted DISC

It is obvious that Excel OOXML has currently many small, but serious flaws:

http://www.robweir.com/blog/2008/05/fractured-yearfrac-and-discounted-disc.html

In fact the problems described makes me think about throwing away the whole MS Office 2007 forever! Boy, am I glad I have never installed it. :-)