As the motherboard has only two expansion slots, both PCI, your options are rather limited. You would need to purchase a PCI graphics card, which probably isn't worth the money.
Yes. Any computer manufactured since 2002, including the Intel D945GCPE, can support a theoretical maximum of 144 petabytes (144 million gigabytes) per drive.
It has a motherboard-integrated graphics chipset by Intel: Intel Graphics Media Accelerator 4500MHD
Yes, that is determined by the ports on your motherboard. Once you have a card that will work then you will go into the BIOS and disable the on-board graphics
No, you cannot.
Yes. Some relatively recent PCI graphics cards are available, which will fit into any of the three PCI slots on the motherboard.
igfxtray is the Intel Graphics Accelerator Helper tray application, which allows you to change settings on your Intel graphics system on your motherboard. It it a normal application, and not spyware or a virus.
I am assuming that you are referring to The Intel® Desktop Board D845GVSR. This Motherboard has onboard intergrated graphics, but does not have an AGP slot available, However there are 3 PCI slots available. So the answer to your question is that without an AGP slot you are restricted to PCI or ONBoard Graphics with this motherboard.
buy a PCI express graphics card and install it , simple.
Potato Peels
No, that motherboard is an ATX form factor motherboard and thus incompatible (not to mention too large) to install on that system.
yes
An update for a program to fix issues with NVIDIA cards will not have any effect with Intel graphics. You cannot use NVIDIA-specific programs on your Intel card.