I'd say that Colony would be the best overall introduction to In Flames, and the version I got has the awesome Golliaths Desarm Their Davids as a bonus. Songs to download should include: Embody The Invisible, Golliaths..., Jotun, Swim, Trigger (album not crappy single mix).
Personally I love R2R. I thought it was refreshing for them to do something different since Clayman felt a bit directionless (although it still has loads of great songs). R2R has a great production (drums!) and I particularly love the ballads which were quite a daring thing to do (especially the country parts on Metaphor) and the album version of Trigger has an awesome structure. However, I really really miss all the proper lead guitar playing which is only really present in a few tiny places (Dark Signs), there are virtually no solos or particularly interesting instrumental sections and I for one am getting pretty tired of the 'heavy nu metal' approach of shouted cruchy verses over-complimented by very singy slow obvious choruses that a lot of bands are going for at the moment. Transparent & Egonomic are also probably the worst tracks the band have ever done. Despite all this, its still a really good album but has little in the way of real classics and I hope the next one (aparently leaked over the net already...) is very different.