Do you have an Intel or NVidea graphics card? There's a video download for Vista 32 for each of them depending on which you have. It's either Intel Graphics Driver - Lenovo
or NVIDIA Display Driver - Lenovo
. But I don't know which from what information you've provided.
Download Belarc Advisor Belarc Advisor - Free Personal PC Audit
and it may assist you in idenifying what you have on your system.
There's no keyboard driver I could find, and even if there were, I don't think the keyboard is the issue - but rather it is the graphics card driver, the graphics card itself, or the monitor. Otherwise you could control it with power options and that isn't working either and has nothing to do with the keyboard. All we can really do is update the graphics driver - the other two are hardware problems. It might also be a general system problem - but that will take some time and effort to trace down.
I hope this helps. If not, post back with where you are stuck or what happened (or what didn't happen) and we'll go from there. Perhaps there's another setting somewhere that can control brightness on your computer - I'll check the site to see if I can find anything.