Seems I'm
not alone - other people are having problems with Excel 2007 taking more than 8 minutes to do something that's almost instant in Excel 2003.
Basically, Office2007 and Vista are both shit, slow, and don't add anything except a new UI. I love the new UI to bits (yes, I even love the god-damned ribbon that everyone for some reason seems to hate), but I can't put up with the incredible slowness and buggyness. It's not that I'm refusing on principle, it's just that it's not a usable product.