It's refreshing to see folks choosing their tools based on results rather than hype and what they've heard is "pro"...Acid's reputation isn't exactly stellar, but from what I've seen it's hard to beat for sample manipulation. Even if you don't use it as the main app, it's good for timestretching vocals to a different bpm and then sampling it - nothing I've found is more convenient in that respect.

Alongside Acid, another good one for throwing around samples with ease is Renoise....all the bread and butter of making dance music (sample browsing, sample editing, hermite envelopes with looping and LFOs, keymapping, effects, sequencing with sample offset, automation) on three tab windows. It is, however, a tracker, and as such lacks a piano roll (which is a mixed blessing and ups the initial learning curve), but it has the standard sequencer stuff that trackers were missing, such as MIDI in/out, VST support, 96k/32 bit sound quality etc. Definitely worth a look if you're primarily about throwing samples around...