Don't know about W7 32bit, If must be a W7, i would go with "Starter", which is only 32bit but up to 2GB ram, or "home basic" 32bit for up to 4GB ram. Any 32 bit Windows is better choice then any 64bit Windows - as i found.
Mostly because Soundcard drivers, so not only Marian's. Also because W7 has different sound management then XP which i found very anoying sometimes. Also, i found that W764 has actually worse multithreading for CPU cores then XP32..
And one thing that i still need to 100% prove myself, is that ST itself has problems with ASIO+Juli@ on 64bit system (tested XP and W7).
https://www.youtube.com/watch?v=tN3qn92R0SE