Recorded Actions and Batch jobs

Since you mention that you have both CPT and CPTX files it might be worth mentioning that your goal of just opening them, chaning the preloader percentage before save and close again might not work out as planned. 

Have you considered the following issues?

Are you intending to open the CPT files in the same version of Captivate that created them, or were you thinking of upgrading them to a later version such as Cp5.5?  If so, you'll need to do more than just change the preloader percentage.  You'll also need to change the path to the preloader itself since each version of Captivate is installed in a different directory in Program Files. 

Were all of the CPT projects set up as AS3 with all AS3 components, or were some of them AS2 and therefore would need to be reviewed and tested to make sure upgrading to a Cp5x version did not have other impacts?  Projects that were set up as AS2 would need to change preloaders, skins, and any animations over to AS3 before the upgrade would be successful.

CPT to CPTX files will also experience font size issues since the font rendering technology changed in Cp5x.  So you'll probably need to go through those projects and fix a lot of issues in text captions.

And another one to watch out for:  After upgrading projects from CPT to CPTX the Continue button on the Quiz Results will often cease to work unless you remove and replace the Quiz Results slide.

This is not a complete list of potential upgrade issues.  What I'm trying to sound here is a warning that, unless you use exactly the same version of Captivate that created them, making any changes to these files could turn into a much bigger job than you hope.  There could be weeks of work involved trawling through each project file one by one checking for issues.