I just got an old computer from a family member and i really need to put some new hardware in it.  Right now it has a 40 GB Western Digital Hard Drive WD400 and  I don't even see a video card.  Basically I just really need to know if a new Western Digital Hard Drive (I'm looking at one with 500 GB right now) and an NVIDIA GeForce 8800 GTX would be fully compatible with the Motherboard.

 
If my memory serves me correctly that motherboard is for socket 478, uses DDR1 and AGP and no matter what cpu you would ever find to fit that motherboard it will underpower that video card, not as if you could fit it in the first place.
 
The 500gb is most likely wont work nether, but has more of a chance then the rest, your better off with a whole new box rather then a patch job.

I was going to get a new computer but I just don't have the money to buy a new computer and I just did a little bit more digging on my own and I'm not going to get the graphics card but I do want the hard drive.  Would I be better off going down to a 400GB instead of the 500GB?  

No, no modern video card will work in that mobo, it does not have AGP or PCIe...only PCI.  As for the HDD, just make sure you get an IDE model, not SATA

 
Alright thanks a lot.  I need to make sure that the one I was looking at is an IDE are they still common or no?

They're easy to find now, but not for much longer.

i just got a compaq with the same motherboard. when i start it the monitor shows nothing, not even the blue screen, and no beeps. where should i start diagnosing? oh, and i accidentally stuck my fingers in the processor fan while it was running, and broke a couple fins off. now it vibrates badly; what can i do about this?

ATI still puts out AGP Video Cards. I used an HD 2600XT with AMD Athlon XP 2500+ and watched Blu-Ray Movies! Gaming though, was lacking... CPU limited
 
Should be able to get an IDE to SATA adapter, tho the BIOS still has to support the larger sized HDD. Maybe a pci sata card might do the trick.