How can I find the exact specs of the video card I have installed?

[roccenstein]

My computer came with an Nvidia GeForce 8400 GS (Yeah, I know it ain't that great, but I couldn't afford anything more when I ordered it, and I figured I'd upgrade later).  Anyway, my video card is supposed to have 256mb of ram, but when I ran the "Can you run it" function on the website www.gamespot.com (a small program that analyzes your system to determine if your computer can run whatever game you're looking at), it said that I have 512mb of video ram.  Apparently, the GeForce 8400 is available in a 512mb variant, but that wasn't what I had, as far as I know.  So, short story long, is there any way to definitively tell what the specs are of the card I have installed?  When I view it through the device manager it just tells me its the GeForce 8400 GS, but nothing else.   Thanks!

[Calum]

This is most likely a technology called TurboCache, whereby the graphics card has its own VRAM, and borrows system RAM too so it has more RAM available.  So you could have got the 256Mb variant, and maybe it is borrowing 256Mb of system RAM too.
GPU-Z should help you out with the exact specs.
Hope this helps.