You should be able to find the DVDs of the seasons for sale on a place like eBay or at a website that sells DVDs. You might not have realized this, but downloading the episodes themselves is considered stealing, and is punishable by law. After all, if nobody buys the episodes and downloads them instead, what is the point of releasing the episodes for sale in the first place?
This topic is now closed for discussion...
...well, sort of. You can still talk about where to buy DVDs. If you want me to re-open this thread with that as the new topic, just PM me and I will re-open it.