I let it finish it's reading of the library and whatever naval gazing it needed. That took about 4 hours and after that, zero impact. I have a rather simple dual core CPU, 3GB 2GHz machine.
I have a Compaq PC, which I purchased in September of 2008. It runs Windows Vista Home Premium. It works great ... until I install iTunes. Then it slows to a crawl or freezes completely. Twice I've done a complete system recovery, after which my computer worked just fine again. Each time I reinstalled iTunes, though, my computer's performance dropped off again. I thought iTunes 7.2 and above were supposed to be compatible with Vista. I've been installing iTunes 8. Any thoughts or suggestions?