Of course go for the iMac, if you got the money for it. I know quite a lot of ICT guys who switched to iMacs/iBooks.
I myself got one of the cheapest laptops available. Also I got quite some USB troubles, but I think the built-in usb port isn't functioning as it should. Because, for instance, I got an USB soundcard wich is fussing around when I am using both my external harddisk and the soundcard at the same time on my built-in usb2 port. But it isn't when I am using my pcmcia usb2 card. Also, certainly usbswitches are a better idea than usbhubs, to prevent collisions.
I'd say try first the cheap solution :-)
