Right-click on "Computer" in your Start Menu and click "Properties" (or Control Panel -> System)
Dude, if dxdiag isn't picking it up, properties window isn't going to pick it up.
Where do you think properties gets its info from?
There's a sticker on the comp that says intel pentium
Anyway, sorry, but there's no way your PC will play it any better than on lowest resolution and lowest detail. It's an old system that's quite bad, sorry.