iBooks are great if you want something small and with good battery life. They do just fine with email, web surfing, playing music, looking at photos and MS Office. Besides games, you can do pretty much everything you can on a PC.
If you want to run your Windows apps on it you can get VirtualPC, but is very slow.
Go try one in a computer store somewhere to get an idea. If you do go for one, make sure you get as much RAM as you can afford.
There are plenty of cheap PCs too and for basic use they will all be about the same.
goates