Ah! now that is a good question

Speed is irrelevant, as an 8x card will support lower speeds.

Depending on the AGP card it will either work fine or be unstable with artefacts appearing on the display.

I believe that quite a few of these cards actually detect what they have been plugged into, and autoconfigure themselves.

Incidentally, although AGP 3.0 is normally 0.8v you do get some cards that are 1.5v which is the same as AGP 2.0.

The specification that I read for the FX 5200 says that it requires an AGP 2.0 slot as a minimum, from which I take it that it will be compatible.

As I mentioned in the other post, 512Mb of RAM is not a lot for an XP machine that is running anything remotely graphics intensive. It is fine for surfing, standard office type functions, e-mail and so on.

You will have to tweak the game settings to the lower end of the range, but this might well be acceptable if they haven't seen anything better

What you have is basically a low end office machine of that era. Anything I have from around then has a P4 1.7Ghz or better or an Athlon XP 1900+ or better all with 1Gb PC2700 DDR.

I guess it all boils down to how keen gamers they are?

Certainly warn them not to try the latest games and try to download a demo before buying anything.