Just one thought on this issue....
I recently installed TSL (again) on my XP rig. I had the BoPC version of K1 installed, as it stays in the HDD permanently.
I did normal XP installation, as in, uh, install it. Updated with patch and HQ's. Went to start up a game.... and it started up just fine?!?!?
I thought for sure that there would be a Securom issue, as there always is, thus why I keep several versions of that .exe archived from ones they have sent me over the years. However, not this time.
My point: Whatever securom version they use in BoPC does not get overwritten or touched by TSL installation, and then carries over to prevent Securom issues for the TSL install. Strange, but that seems to indeed be the case
XP has changed over time though... It is quirkier running this game than it used to be, especially at start-up: it always starts in Windowed mode now, even though I have not played with those options in the Graphics Settings.