It's start->run: dxdiag. The 3rd page gives you information about your graphiccard.
For the 3d RAM, be sure that 3DGS can't damage your hardware in any way,
thats not possible.

But make sure that you have the latest Windows 98 patches installed, that your DirectX is
updated to the latest version (9.0c) and that your graphic-driver is also the newest.
Beside that, go to
www.memtest86.com , download their tool and run it on an bootdisk,
to check that your RAM is not damaged in any other way, which would explain the crashs.
old_bill