Yeah. Windows, as far as I can tell, shows iowait CPU as normal CPU usage.
Linux, at least, shows iowait usage in a separate bin, letting you know when you're I/O bound.
Nearly every time I've found my system unresponsive/slow, I've noticed my CPU utilization bar on my system monitor widget is almost entirely green. Green = iowait.
In a number of cases, the iowait was high because my system was swap thrashing. If your system bogs down under heavy multitasking, it's much more likely you need more RAM and not more CPU.