Hell, 1066 could be viewed as two groups of Vikings fighting with some Saxons for control over the island.
How Viking (both in terms of culture, ethnicity and ancestry) were actually the Normans by 1066?
Aren't Vikings by definition Pagan (Pagan deities were integral part of Viking culture)? The Normans were Christian.
Modern population of Normandy also does not seem to be genetically Scandinavian:
http://www.eupedia.com/europe/european_y-dna_haplogroups.shtml
http://www.khazaria.com/genetics/swedes.html
Just 1% of Normandy population has R1a haplogroup whereas in Germanic Scandinavia this haplogroup is much more frequent (15% - 26% depending in which country). The same is the case with haplogroup I1 which is also much more frequent in Scandinavian countries than in Normandy.
It is also well known that the Normans were French-speaking when they came in 1066, so perhaps they were heavily mixed with local French population. Or did they preserve the "purity" of their Scandinavian ancestry and just adopted the language, without mixing with the local population?
Here is a good website describing the composition of William the Conqueror's army (including a list of eminent men who led their own troops):
http://www.battle1066.com/wforce1.shtml
We can see that apart from forces of his own Duchy of Normandy, William also had allied forces provided by the Bretons and by Flanders.
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Fighting methods of the army of William the Conqueror were also totally different than those of the Vikings.
The Vikings did not rely on heavy cavalry. The Vikings did not use cavalry at all. While the Normans are famous for using shock cavalry, and for holding spear underarm (which eventually gave rise to development of new weapons - lance, and long lance - improved versions of spear for cavalry).
The Vikings also did not rely on archer support - at least not to the extent that William's army did at Hastings.
The Housecarls employed by Harold resembled the Vikings much more (there could actually be foreign mercenaries among them).