In reply to antdav:
> Xenon's seem very selfish, i had them on a company car and could see way in the distance but so many people who have them also angle their lights up and blind everyone else.
To be legal (ie to comply with Construction & Use Regs, I think) xenons have to be in a self-levelling mounting. This is specifically intended to reduce the risk of them blinding other drivers. It still depends on having the lights correctly aligned to begin with, though (and that isn't always straightforward: sometimes you have to tell the on-board management system that you are aligning the headlights, otherwise it will just move them back to where they were before you started!) Mind you, even ordinary fliament headlights can be a right menace if poorly adjusted.
You also have to have a means of cleaning the headlamp glass if you fit xenons, either a high-pressure spray or a spray+wipe. This is to reduce the risk of the bright light being scattered to places it shouldn't be by a film of grime on the glass. On my car the headlamp washers fire off automatically the first time you wash the windscreen when the lights are on, and every fifth time thereafter. I know of some people who have had their on-board management systems reprogrammed to make the automatic headlamp wash less frequent, or to disable it altogether. The main reasons they offer for this are (a) that it saves washer fluid, and (b) that they don't like getting washer fluid streaks on their freshly-polished bonnet. This merely reinforces my view that more people than you might expect are really are too stupid and irresponsible to be allowed to own a motor vehicle.
Overall,
legal aftermarket xenon installations are an expensive way to go - it's not just a question of swapping the bulb. Hence, probably, why so many seem to be badly adjusted and verging on the dangerous - they've been done on the cheap and aren't legal. I believe that xenons are more efficient than filament lights (the Osram replacement xenon bulbs for my car are rated at 35W, for example) but there's no way on earth you could use that theoretical saving to build a viable financial case for fitting legal xenons!
Basically, it's not worth the hassle of "going xenon". Buy and fit the higher-power filament bulbs by all means, but please make sure that your headlights are properly aligned at the same time.
Judging by frequent practise round these parts, though, the proper way to drive on dark winter mornings and evenings is to use side lights plus fog lights. Headlights are for wimps...