My HD5770 finally returned yesterday!
On refitting the card and booting, Windows 7 loaded the earlier drivers from the secret stash somewhere in the depths of the Windows folder maze, if I'd used DriverSweeper earlier, I think these would have been removed and W7 would have loaded the vanilla drivers.
From Device Manager I did > Update driver > Browse my computer ... > browsed to C:\AMD\Support\12-3_vista_win7_64_dd_ccc\Packages\Drivers\Display\W76A_INF (the recently extracted new drivers), and DevMan installed drivers only.
No sign of any CCC components or other ATI utilities anywhere, no AMD/ATI folders in Program files or Program files(x86), no reboot required, no extra processes set to autorun, no new Windows services loaded.
So, for anyone experiencing problems that may be linked to buggy graphics drivers/utilities on an ATI/AMD card, it's not too difficult to remove the old drivers, using DriverSweeper to be sure all traces are removed, then installing bare drivers to test stability. I'm pretty sure this method would also be applicable to Vista and XP.
For users with a small SSD boot drive, this method may save 100MB (or more) of unnecessary bloat. The AMD extraction folder can be safely (re)moved, freeing up a further 225MB of valuable drive space.