E-400 - as for E-510 but smaller, lighter, less features, no IS, or Live View but was the smallest, lightest dSLR in the world
E-410 - as for E-400 but added Live View, larger buffer (7 RAW burst instead of 5, and unlimited jpeg burst at 3fps)
E-420 - 2008 model as for E-410 but adds wireless TTL flash support
E-450 - 2009 model - essentially identical to the E-420 apart from the addition of 3 Art Filters, a new processor and an improved LCD display.
E-520 - as for E-510 but adds wireless TTL flash support, ART filters
E-620 - early 2009 model - improved version of E-520; 4fps 13mp, IS, swivel LCD, 7 point AF
E-600 - late 2009 model - budget version of E-620 w/o illuminated rear controls and fewer Art filters;