GTA IV on PC - Configuration help needed, Basic Graphic Problems Options

[Purple Pete]

While I certainly don't expect to run GTA IV (PC) with anything near max settings, it's simply not playable even when I have it at lowest settings or when I run it in SAFE MODE. During the game's intro scene I felt like I was on the ship from the Philadelphia Experiment with everything phasing in and out of reality. Often the radar graphic is missing, even while points-of-interest on the radar appear. I often can't escape out of the game because it won't switch to the menu screens and I have to ESC back to the game. Sometimes I'll see bands of garbage lines running through screen. Everything is dark and shadowy. When I'm driving I can't see obstacles until they are are less than 1/2 of one car length in front of me. The shadows on walls and surfaces are very obvious circles within circles with no blending. I've tried turning everything to the lowest settings or playing in SAFE MODE. GTA's auto configure dumps me into the very lowest settings even though the memory allotment shows a lot of room.

Anyway, my PC is less than 2 yrs old. Shouldn't I at least be able to play this game in San Andreas quality graphics? I'm feel I'm missing something obvious. Any help is greatly appreciated.

Windows XP service pack 3
Core 2 Duo E6600 (2.40 Ghz)
EVGA Geforce 7900 GTO (512 MB, GDDR 3) - New driver 178.24 - no Overclock except as it was out of box
2 GB memory (Corsair XMS2) DDR2 SDRAM DDR2 800 (PC2 6400)

I've tested with the 169.44 Video Driver as well, but no improvement.

My card is not DX10. I'm a little confused about the Shader feature or how to use it. I assume it's on by default. I have not tweaked the card in anyway. Everything is on out-of-the-box factory settings.

I've used Nvidia's control panel, under manage 3D settings and selected gtaiv.exe, but I really don't know what settings to tweak.

I have the DVD version of the game. I installed everything and successfully authorized the game online. However, I did not set up any Social Club Accounts and the only Windows Live account I created was an Offline one (because it's the only way you can SAVE an SP game). After that I just used my firewall to block all internet access from anything GTAIV related.

What a bother for someone who just wanted to play the SP game. Even with all the side apps installed, it still takes almost 2 minutes for me just to get to the start menu, not counting the lesser menus I have to click through to get there. There appears to be practically no custom configuration options for keyboard play other than toggling on/off.

I've wasted hours of my time and it's still unplayable. I'm very disappointed.

Any help or advice is greatly appreciated