What I've heard is, it's illegal for a US-based company to sell or install HID headlight kits (I believe it was effective after September 1, 2003). However, you can buy them on eBay or over the Internet, and install them yourself. I believe that shops will be fined $5000. per instance if they are caught selling or installing HID kits.
Anyhoo....here's a pic of my MSP with the Catz Hi/Low HID kit....I do get to keep the functionality of my high beams, while having a brighter, seemingly more solid beam of light for regular night time driving. Yes, they are bright, perhaps borderline blinding. But the way I see it, I wanna be sure someone sees me coming. *shrug*