...So even after a brand clean windows 7 complete full reinstall from factory, and installing again SH4 V1.5 without mods, no water transparency

(either DVD version or downloaded version)
Can't be drivers (they are now stock) and can't be any Nvidia bad settings either.
Only remaining thing is my Zotac 580 graphic card wich doesn't allow water transparency for SH4...and i really don't understand why!!!
Though, SH5 is working fine, and water transparency is nice...
Go figure