VIA 4-in-1's really needed for XPpro?

Do I really HAVE to install them? Everything seems to run quite fine to me...

As long as your system is running fine, there's really no need to install/update the 4in1's since they already come preinstalled with XP. When I say they come preinstalled, I mean XP comes with the 4.34 version of the drivers...I believe it is. The newer 4in1's since the release of XP include support for the newer chipsets, newer AGP driver, controller drivers, etc.

It's up to you really...whether or not you want to try out any of the newer revisions of the 4in1's. You may notice a slight performance improvement over the default drivers, or you may notice a slight decrease in performance...either is possible depending on the version of the drivers you install and your system in general. If you do decide on upgrading the 4in1's, I would suggest creating a restore point beforehand...just in case the newer drivers cause you any problems.