Osram and Philips both do superb road legal upgrade bulbs that can be obtained from
www.autobulbsdirect.com
Don't retro-fit HIDs. The law is grey and most police won't be suitably informed but it's still technically not compliant with the law.
All HID cars need to have self levelling lights (ie. not a dash mounted switch) or self levelling rear suspension.
They also must be fitted with headlamp wash systems.
Even if you retrofit both, the headlight assembly has not got type approval for HID fitments.
It's a moot point, and the biggest risk is that your insurer will consider your car to be modified. This is fine until you need to make a claim. And they WILL try anything to wriggle out of paying up.