Vegas 7.0e crashes on startup...
 

I see "Direct-x Plugins" before it crashes, before it would load projects and hang, I've reinstalled and reformatted my computer (with Vista and XP , SP1 and 2)

With Vegas 7.0a, d, and e ... nothing works :(

Try switching video cards...
 

Just a few thoughts...

Plug an old VGA graphics card in your computer and see of you can get vegas to start. If it does then the DirectX drivers have a problem with the video card drivers and then.... look for updated DirectX and graphics card drivers..
Possibly get a new graphics card?

Might also be related to audio hardware. Disable/uninstall audio drivers in Device Manager and try launching vegas. If it works then get a cheap audio card and disable on-board audio systems/drivers...

/magnus