Keith. it's essential that whatever you sample from a track shares the same tempo when mixing. This is where Acid Pro comes to the fore. It has a poweful beatmapper function where you can accuractly subject the sample to your required BPM. Look on You Tube for the subject of beatmapping in Acid.
Here's a link to Sony's promo wab page where it mentions beatmapping it's at the bottom of the page.
http://www.sonycreativesoftware.com/acidpro/mixing
Here's an example of bearmapping in use from two songs with drastically differing tempos. http://soundcloud.com/buffalow-girl/remix-police
Bri. aka Buffalow Girl


