Kind of happy that they actually give good advice about the Celeron. They have processing speed, but the lower cost of them comes from not having enough cache which causes the processor to spend a lot more time moving data around before processing, so it ends up slower than a lower clocked but higher cached computer processor.
They were pretty decent when they first came out when processing speed was king, but as speed hit a limit, because of heat generation, the importance of cache for performance can't be overlooked anymore. The Intel Celeron became a trap for those that don't know better.