Most of the software that can be bought for a PC can also be had for a mac as well. If not, Virtual PC is the go.
If you go for a Windows Based Laptop, be sure to get an Athlon64, This will enable you to upgarde to Windows Longon if they release it.
iBooks are more the cheaper version of the G4 Range, There fine to use (I have one myself). They are generally more user friendly than Windows XP, and are MUCH more secure.
Mac OS X Has far less security holes, gets a lot less spyware and malware than a PC.
Just keep that in mind when your looking for a decent lappy.