thats a bit carp
As bill gates famously said..."I can't see why anyone would need more than 640k memory" Although there's talk that, that was just a rumor. Point being though when windows 95 was first developed, 4gig was almost unimaginable.
for 64bits OS you can plug any amount of RAM between 512MB to 8GB (some new mobo can max to 16Gb or 24GB) -- for 32bits you cannot pass 4GB RAM.