As long as you have all your project media available, you’ll be fine.
No need to overwrite your previous .veg file. You should be saving incremental versions as you work anyway.
Also, it’s not a good idea to keep your only .veg files on the same drive with your media. If your drive fails, you’ve got nothing.
Gary Kleiner
Learn Vegas and DVD Architect
http://www.VegasTrainingAndTools.com