I was first introduced to the story of these knights in the works of that brilliant storyteller John Julius Norwich, who sadly passed away a couple of years ago. He wrote Normans in the South and followed it up with The Normans in Sicily. For many years I used a Siculo-Norman army in WAB competitions with some success.
This book gives a brief history of the Normans in Italy, from their arrival as mercenaries and bandits to Papal recognition after the Battle of Civitate in 1053. They fought the Lombard and Byzantine rulers but also assimilated the peoples of the region. The author makes the point that there were never huge numbers of Normans, although their ferocious charge was often the decisive tactic.
There are chapters on the organisation of the Normans and their armour and weapons. They were organised into small tactical units known as conrois, typically 20-30 men. They organised the land they acquired into the feudal system, welcoming other north European troops and enfiefing locals. The Kingdom of Sicily included Muslim units and incorporated local leaders. This provided light skirmishing cavalry and fine archers, which gives this army balance.
As usual with this series, the book is profusely illustrated with photographs and colour plates. A very useful introduction to the period.
On the subject of Normans, the latest edition of Hobilar, the journal of the Lance and Longbow Society, is a special on the Normans. There are articles on the Normans in Wales, Sicily and on crusade. It includes my own article, The Normans in the Balkans. There are also reviews of a number of recent publications on the Normans.
My 28mm army has figures from a number of ranges. The wargamer is not short of options when it comes to these warriors.