I would like to upgrade my headlights.

I did a HID headlight conversion on my last car and it was great.
What company/website would you guys recommend?

I would like to change my fog lights too, preferably make them purple. I would like to make the headlights simply white. i am assuming that making the conversion truly will make my visibility at night better. There's no point if it doesn't actually help.

Has anyone else done this?
What is the job like DIY?