No, do not do this.

The W210 headlamps are largely plastic. 100 watt H7s would produce much more heat than the standard 55 watt units and could melt the plastic reflector and housing. The "science of cheap" has come along way since the W126, so wiring, connectors, etc are built with less safety margins. Relays, heavy gauge wiring are required for high wattage bulbs and running these into a modern headlamp is a bit more complicated than with a 20 year old car. Plus you will confuse the bulb out computer. And there are the legal problems on running high wattage bulbs.

If you want your W210 headlamps to perform better, make sure they are clean, not pitted, and aimed correctly. You might want to try 30% or 50% plus H7 avail from Osram or Philips. Stay away from tinted bulbs. If you do not have the Xenon (H.I.D.) headlamps that were optional on your car, you could install them. Hella has a kit to retrofit these along with the leveling and headlamp washers. The Hella H.I.D. headlamps are even avail in a smoked look that I do not believe hurts performance as the inner bezel(non functional) is black instead of metalized making the lamps appear black.

Strange, but they are not shown in the 2005 Hella cataloge.