For some reason, I can't use my original screenname. Doh!

Warsaw, good point about different sets. I had some toys called Construx when I was a kid, and I never called them "Construces" or something weird like that. I think the difference with Lego is how ubiquitous they are. I live in Hong Kong now, and there are Lego-building classes advertised everywhere.

It's like pes' point earlier about Band-aid bandages. If my son scrapes his knee, I ask him if he wants a band-aid. If he has several scrapes, I might have to put two or three band-aids on him. Band-aid started out as a brandname, and it's evolved to the point where it's used as a common noun. The Lego company doesn't want that to happen to it's brand (some of their international trademarks have already expired), and thus they engage in their campaign to dictate how we use the word "Lego." (Here's one story about how Lego has failed to keep the trademark on their design - http://www.independent.co.uk/news/world/europe/eu-judges-rule-out-lego-trademark-2079150.html - even though that design was borrowed/stolen from another company before Lego bought that company - http://www.cracked.com/article_20025_5-world-famous-products-that-are-shameless-rip-offs.html )

We're getting into the difference between prescriptive and descriptive definitions. Generally, dictionaries are descriptive in that they describe how a word is used in a particular language. If enough people start using Lego as a common noun, that usage will be reflected in a dictionary like the OED. The Lego company, however, is aiming to be prescriptive, to control the word's meaning and usage. In language, that's like plugging your finger into a dam's wall and hoping you can prevent a flood.

Goofy, just accept that the usage of the term "legos" varies depending on where you are in the world. Just as my usage of "legos" sounds odd to you, so does your usage of LEGO as a collective noun sounds odd to me. Growing up in the US, I loved legos, as did many of my friends and family, and no one ever used LEGO as a collective noun. The English language is a hairy, wild thing, and nearly every rule has an exception to it.

As far as collective and non-collective nouns go, you'd no doubt say "I have much LEGO." I'd say, "I have many Legos." I'd also say, "I stepped on several Legos on my way across my living room last night." And yeah, I'd also say, "My son has about a million Legos." =)