nihil not surprising there is no AGP slot, the AGP is built-in for the integrated video thus not available for external cards.
Only if the manufacturer decides to make it so. I recall buying Dell Optiplexes (PIII) back in 1999/2000 that had onboard graphics and supported an external AGP card. I also have an AMD Athlon 1900+ (1.6GHz) that supports both onboard and AGP slot graphics. What you are describing would be typical of low end office equipment of the day. Sony make this machine out to be something much better than that.

Sony marketed this machine as a "home entertainment" package. And from the processor, I would guess it to be 2003/4 vintage? By that time:

1. PCI video cards were obsolete.
2. PC 2100 memory was obsolete.
3. World + dog knew that you did not ship Windows XP with less than 512MB of RAM. Unless it was for a very basic office environment.
4. 180W PSU ????????????? hell, I didn't build with less than 350W from 2000!

@wiskic10_4

I guess you are trying to "make a silk purse out of a sow's ear" as we Brits would say

If you are getting artifacts from the video card in "normal" use, then I would send the card back. This is something that I would generally associate with a hardware problem, rather than firmware or applications. As you have already noted, you could confirm this on another machine.

Are you sure about the 180W PSU? that seems very low, even for a miniATX, which that box is not. Obviously the 500W Coolermaster is total overkill

My guess is that the best you can hope for is to find a second user PCI gaming card.

As I said, I would be inclined to start over, and the 500W Coolermaster would certainly fit into that?

Good Luck!

@ IKnowNot,

Many thanks for that very interesting link. It isn't something I have really looked into before.