How does evolution work?

There are differing opinions on the subject, but generally there are two takes.  First, evolution is slow, it takes a long time, a long long time, perhaps even longer.  The other theory is that it is quick.  Something happens that radically changes the species.  This is often called "Punctuated equilibrium," or "evolution by jerks."  The former is sometimes referred to as "evolution by creeps."

So, how exactly does it work?  Evolution either way takes time.  You can't predict when evolution by jerks will occur in nature, so it is hard to observe.  Evolution by creeps in nature is even harder to observe, it relies entirely on the so called "fossil record."  So, I will use an example from modern science, namely computer operating systems.

Take Windows for instance.  Every 5 years or so a new OS is released, this is evolution by jerks.  (It must have been a jerk who came up with "windows genuine advantage."  Advantage my eye!)  In between these large jumps small changes occur, these are called windows updates.  These updates provide variation in the population, and are generally good.  For example, my other computer is running windows 98 sp1, and this has sp2.  This variation weeds out weaker computers.  For example, computers without updates to fix all the problems windows has will become infected with viruses and spy ware and stuff and stop working.  That person then gets a new computer, ditching the old one on the side of the road.  Some of these jerks in the development don't work and leave the now generation worse than the previous generation, such as Windows ME. 

Evolution by creeps is typified by Linux.  All those creepy people living in moms basement working on computers making constant updates.  I run Ubuntu at times, and every 6 months a new version is out.  Don't know what is different, but I am told it is much better than before.  But at least I don't have to pay out the nose for it (see Jerks above).  Linux has much more variation than Windows.  Each "distribution" has different features and accessibility options.  This is better than then the "themes" used by some.

Mac OSX is also out there, but I haven't really used a Mac since the Apple 2e in school.  I miss playing Oregon Trail. 

But anyway, how do these changes in nature occur?  The genes of a given species change by several methods.  The first is random mutation, this leads to corrupt files 99% of the time.  This is like the auto correct function in word processing programs.  How often do they actually get the write word, rarely.  Sometimes they do.  The remaining percentage of times it changes the word to something even better.  Personally I have never seen that happen, but statistically it could.

There is also "horizontal gene transfer" where genes move from one species to another different species.  This is currently being done with genetically modified crops around the world.  It can also be seen in the computer world.  For example, compare OSX with Windows Vista and Windows 98.  There seems to be a lot of things which have moved to Windows in this last evolutionary jerk from OSX. 

There are other modes as well, such as hybridization (running Windows on Mac Hardware), and migration (running Linux on your XBox), and selection (asteroids killing dinosaurs). 

Thanks for the Questions, and comments.