option keys are (always !) stored on the acquisition board (or eventually on the interface board to it), so even if you change the hard disk, the keys are kept...
Regarding X-Stream I scopes, yes, the acquisition board drivers exist only in 32-bit versions, and even worse, these drivers have more or less serious issues with multi-core kernel versions (of XP), X-Stream II scopes (even 32bit) are the only ones for which the drivers support multi-cores.
And yes, be it for X-Stream I or II, the latest version of the 32bit software is currently 8.1.0.1.
Should be confirmed, but your WP7K should be compatible with that version... although not officially supported by Lecroy. Just upgrade to XP first... I've got a WR6K in 7.x, no issue whatsoever... the only issue is indeed that X-Stream I drivers are no longer included in the installation package since some 7.x version, so you need to install some 6.x and upgrade afterwards...
So this is in fact the main reason of my question... hard disks fail, disks get corrupted, so a re-install from scratch is not that unusual, and I was wondering if this happens when one has 8.x installed, and you need to start over with some 6.x (to have the correct drivers), what would happen to the (apparently) previously up-converted option keys...
Strange btw that Lecroy changed that recently... as it was to my knowledge one of the few, if not the only scope maker from which the option keys stuff had not (yet) been cracked... (there are enough threads for other brands on this forum... ;-)