I have had some problems with 64-bit windows 8 and some BL games and I wanted to go ahead and post a list of the issues I've had as well as to ask for some help for those I have yet to solve.
- Kimi no Naka no Palladium requires the solution posted by snowgoose here.
- Hitotsuya Monogatari does not work with Windows 64 bit
- Jackin! does not work with Windows 64 bit
- It seems Ein is aware of the issue with these two, but I don't know if a solution is in the works
- Apparently Lamento also doesn't work? I don't know this first hand; however.
Edit: Square na Kankei works fine with 64 bit Windows, I still don't know about the other Ein stuff.
Virtual Box works fine for running these older games.
It seems that Cox-Bax also does not work with 64 bit Windows, though I'm not entirely sure as it's not clear on the manufacturer's webpage.
A fairly comprehensive list, but most of the other problems listed there seem to be minor.