Just my two cents, I was able to install and play Warcraft 3 on Vista 64 and play through both the Humans and part of the Scourge campaign. I have the X1900XTX, and used the cat 7.2 drivers at the time.
I think all the DX9 and DX10 talk might be for nothing, has Warcraft 3 came out in 1998 and is a DX8 title.
Make sure you apply the 1.21 patch for Warcraft 3.
System Requirements:
Windows® 98/ME/2000/XP:
400 MHz Pentium II or equivalent (600 MHz recommended)
128 MB of RAM (256 MB recommended)
8 MB 3D video card (TNT, i810, Voodoo 3, Rage 128 equivalent or better) with DirectX® 8.1 support (32 MB recommended)
700 MB HD space
4X CD-ROM drive
My guess is that you might be getting hung at the opening cinematics. Far Cry 64 had this issue, where they changed the format of the movies they used in Far Cry, when I tried to runt he game, the screen would just blank out and sit. I tried playing the movies manually and saw I was getting a codec error (XP plays the movies fine). In FarCry I just removed the movies and it skipped right on to the optins screen