Spotlight Eating Up The Processor

Noticed the other date that mds and mdworker processes were eating up my processor. Reboots didn't seem to have any effect. Turns out that Spotlight is hung up on something. Not sure if it was related to the Leopard upgrade or to something else.
I went into preferences and removed the primary hard drive from being indexed. Then rebooted and added that primary hard drive back to being indexed. Once that was complete these spotlight processes began to behave normally. Of course this recreated the index but considering that they don't eat up all my processor now I'm happy with that outcome. Reminds me of the same problems the MS Windows indexer used to sometimes have.