Since you already have Vegas, you can do much of what Acid can do there. Just use all audio tracks and drag you loop tracks to the timeline.
If you want to use Acid, there is a free version available here:
http://www.acidplanet.com/downloads/xpress/
Or you can download a free, fully functional 30 day trial of any Sony Software here:
http://www.sonycreativesoftware.com/download/trials
If you like CineScore, you might also like Sonic Fire Pro (I have, like and use them both). SmartSound also runs specials on their libraries often – http://www.smartsound.com/specials/index.html?utm_source=InvenReduce909&utm_campaign=trmsfp4
