The really cool thing about Acid is that you can change the tempo of the overall project and all the files automatically adjust to fit. However, when you have a file that is quite long and is seen as a "one shot' and not a "loop", then that file needs to be "beatmapped". In English that just means that you are adjusting the tempo manually. Run the beatmapper wizard and be sure to check the "maintain pitch even when temp changes" checkbox at the end. This should stop you sounding like Alvin in his furry friends!
