I love running final cut pro on my mac, and honestly i've never ever seen a pc boot up as quickly, or open a program as fast, or run as smoothly as a mac. As far as video editing is concerned, I think mac has to be the way to go, even if you use premiere. If you are concerned about upgrading your computer there are ways to do it, and mac pros are very accessible/customizable, if you have the cash :\
and if you run vegas right now, stop using it and start to learn how to use FCP, Premiere, etc. They have so many advantages and useful features that don't take long to pick up on.