Neither of them worked on win 7 64, GPU NVidia GTX 295, Intel Q9300. Both had graphic problems and Deadly games even crashed my OS, and I had to restart the computer using the on/off button.
It seems that my GPU and/or my OS and these games are not working well together. Any ideas how I can setup these games to play them?

Are they using Dosbox? Try changing the video rendering mode.

Yes, using Dosbox, can you explain what do I have to do to change that rendering mode? Where do I setup that?

Start -> All Programs -> GOG.COM -> Jagged Alliance -> Graphic Mode Setup.
Direct3D typically works fine for me; experiment till you find the best option for you.

/Yes, that worked for quality, but my computer still crashes and I have to restart it with the on/off button. Any ideas?/
Doesn't sound like DosBox issue at all. Tried cleaning computer internals from dust\checking the temperature of CPU\MB\GPU? Might be overheating (Latest NVidias are notorious furnaces).

The computer is allright, I can play metro 2033 full specs in it. All other games work well. It's an issue with those JA. I kind of bypass the issue playing it in a windows, but if I try to play it fullscreen it crashes badly. I would bet that it's compatibility problems since I'm not seeing anymore complaining. Just would like to find whats the reason so I can play those games at fullscreen. But thanks, I'm playing JA now.

Sounds like it might be a Dosbox issue. I've had trouble with Dosbox 0.73 when switching between applications. Neither 0.72 nor 0.74 have this problem.