Does anyone know if Vegas has a built in Vignette effect? Ive been using photoshop to add one, but would prefer a solution in vegas. Thanks!

You could try the cookie cutter, bezier masking, or:
Apply a grad on a top layer. e.g. a circular gradient
set the top layer to multiply compositing mode

You can use the parent/child relationships to control which layers get affected.

Or just apply a grad set to circular mode, and make the center transparent. Feather from there.