This can be resolved in three ways (at least, on my current computer, running a GTX 560 Ti):
1. Enable 3D acceleration on games that support this. BG1 in EasyTuTu, BG2, and Icewind Dale 1.
2. Set the color palette to 16-bit color, and enable Software Mirror BLT.
3. Use the DDraw Fix:
I've tried all three options.
Option one is the best, if you run a game that supports it. In BG1 EasyTuTu however, the water is still green in Tazok's tent, and on the Durlag's Tower map, even when the EasyTuTu DeGreenifier is installed. The author of the program has already stated that he is probably never going to fix this (and possibly, it may not even be fixable).
The second option works very well too. It seems that switching to 16-bit color mode, and then enabling any of the Software BLT options fixes all the anomalies, but "Software Transparant BLT" slows down the game to unplayable speed, especially in battles. "Software Mirror BLT" seems not to have any impact. It seems the image quality doesn't become worse either.
Just because I was curious I've tried the DirectDraw fix above, on EasyTuTu, IWD1, and IWD2. In all three games, I am experiencing random crashes to the desktop with a hanging / looping sound card, and a need to reboot the computer to get rid of that. Option 1 and 2 have worked fine. I've played halfway through BG1 EasyTuTu using option 1, played several days using option 2, and I played halfway through IWD1 using option 1. No crashes.
Personally, before trying anything else, I'd first try to set the color palette to 16 bit and enable Software Mirror BLT. It seems to solve all problems (at least for me), without any detrimental effects. If you can live with the two green water bugs in EasyTuTu (which are purely cosmetic, and you won't be in those area's for long), then 3D acceleration is the best option for this game, as wel as for BG2 and IWD1.
I have not yet tested PS:T, but I remember that this game is a ****, actually crashing on exit, but fixable by using the Application Compatibility Tool Kit (ACTK), found here:
At some point, I found out these settings by testing, and searching the web:
Select Windows XP Service Pack 3 as the OS in ACTK
Then add the following fixes:
I'll test PS:T in the near future.
Maybe this post is useful for someone down the road.
This computer, running Windows 7 x64 Professional, will be a legacy gaming computer at some point; as will it's successor be. That computer will probably also run Windows 7 x64 Professional (I still have an unused license), so I'll have two computers on hand for old games :)