basically you have series 1 & 2 is200's & similar options for both.
series 2 (from late 2001) have the blackened headlights, black grill, 6 airbags (front, side & curtain), instead of just 4 (frot & side)
the series 2 is 5 star saftey rated - not sure on the series 1 because it doesnt have the curtain airbags)
also the interior of the series 2 has more neutral colours (more black on the dashboard) & the all important centre armrest.
series 2 is the one you want to buy imo.
good luck with the search, they are great cars to drive in manual form especially.
maybe check out my forsale advert :)
cheers
Andy