Help on 1.5.6 - 1.6.4 windows upgrade please

[Richard Strauss]

I have an old working version of Lyx 1.5.6 
(LyX-156-3-25-AltInstaller-Complete.exe) on windows XP. I now want to upgrade 
to the latest version. Which release do you recommend, without having to 
compile lyx manully.

Thanks. Richard