unity won't start?

downoaded unity 3 and it won't start. i have emachine pc with 2gig ram intel core2 duo and windows vista. is it maybe the video? because it's built in intel video card? do i need nvida video card for unity to work? i use gamestudio, 3ds max 2010, maya 2010 and motionbuilder 2010 and they all work fine with this video card.

Try Updating Windows .Net Framework (go to link textMicrosoft update) that should do the trick works most of the time. It Shouldn't be DEP as that checks memory through hardware & software to help prevent malicious code from running on a system. Unity does not have Malicious code.

I would check through every item in the first answer here:

http://answers.unity3d.com/questions/23103/why-does-unity-3-0-fail-to-start-on-windows

Most likely it's DEP though, that's always a pain with these things

Adding Unity as an exception in DEP worked for me. Unity does some hardware intensive stuff. It also lays has a tonne of folder and library dependencies. I’m not suprised Windows 7 sees all that rights-grabbing as dangerous: It is! But also worth it.

Thanks Mike 3!