I checked on dxdiag that the current direct x version is 10? Does that mean it supports Direct X 10? I checked my memory and I have a whopping 807mb video card. It used to be 512mb, and I bought it at 512... I'm using Vista of course
No Vista comes with DX10. This does not mean that your card is DX10 compatible. The card has 512MB of on board memory with a 256 Memory Interface. Add them together to get your full memory.
As stated above only the nVidia 8000 series is DX10. All this info is available at nVidia's web site.