iTunes on my iMac G5 with 1gb use like 23mbs FireFox use about 50, actvitity Monitor use 20(the app thats give me this info), Dock uses 22mbs, wigets use up 23mbs and as low as 12mbs.
Wwith that info iTunes really is not that much of a hog and for what it use vs a widget(that use as much mbs just sitting there) 23mbs is good.