You can download the updated Windows XP Software and drivers here: Support.ASUS.com.
Joanna Stern over at the LAPTOP Magazine blog (she has to be the resident expert on netbooks at LAPTOP Magazine) has written up an article on installing and running iTunes under Wine on a Linux-powered Eee PC 900, includng a step-by-step tutorial and her experiences.
Finally, if you are handy with a soldering iron and want to do a radical upgrade on your original 7-inch Eee PC 4G, well, this might be for you: Eee-PC.de (translated) has a tutorial on upgrading the 4GB Solid State Drive (SSD) to a 16GB SSD. Included are benchmarks. Needless to say, this voids the warranty in a matter of seconds.