Software updates are a fact of life. Since the first days of computing software engineers and programmers have been updating, revising and bug fixing their programs. When a program ceases to be updated, it will eventually become obsolete. You might wish that you could buy one computer and one program and never have to change either, but we are all living in a world where technology is changing daily. Many of the changes to software programs come about as a result to reactions either changes in the hardware or operating systems.
For example, Microsoft had a very stable and useful operating system in Windows XP. But for the need to produce a new product to keep competitive and a lot of other reasons, Microsoft "upgraded" their operating system to Windows Vista. Vista was never well received and many people, after trying the program went back to Windows XP. Now, in an attempt to once again introduce a "new" program, Microsoft is introducing Windows 7 to replace Vista.
Likewise, the chips that make up a computer change. Intel, a major chip manufacturer, introduces new processors all the time, again, to remain competitive. The latest Intel chips have names like Intel Core i7 processor Extreme and Intel Core 2 Quad Processor.
Once the operating system and/or the hardware changes, the software developers likewise have to make changes to their programs. Without the changes, they run the risk that their programs will not work at all at some point.
Genealogy programs change constantly. Versions change and minor bug and feature fixes occur all the time. Here is a list, as of 6 July 2009 of some of the latest release versions:
Ancestral Quest 12.1.17
Family Insight 2009.5.16.2
Family Tree Maker 188.8.131.525
The Master Genealogist 7 (probably a later version but not easy to find)
In every program it is a good idea to check for upgrades periodically, however, in most cases the developers will notify you of software upgrades.