Try and avoid using loops if you can. If they're slightly out of time, they can make a whole track sound sloppy. The best way to use a drum part in Vegas is to load it into the trimmer, highlight the individual drum sounds and drag them onto the timeline. This can be done in Acid aswell, but the Vegas method is a lot easier. You can also adjust the fade outs of each chopped clip on the timeline incase there's any noise there.