in my opinion, they give off more light, especially noticeable when driving along dark lanes wityh no streetlighting, the whole place is lit up a treat.
re: where to buy, good old ebay, and do a search for ultra bulbs H7 for the dipped beam, H7 for the full beam, W5W for the 4 little sidelights, and HB4 for the front fogs. Ive not changed the front fogs yet, bit of a chore involving bumper removal etc, so will get round to it soon enough.
Go to the Mk5 Ibiza FAQ list, and there is a bulb list thread and a how to guide for alot of the bulbs. worth checking out for sure.
Also, no idea bout the 17" wheels either I'm afraid....
And yes, I do realise that THIS IS the bulb list thread.....