It's probably more a wind-up than not, so to speak...
I can speak for Norway: Speed limits are strictly enforced by the police. I can assure you that if you're caught while speeding, it will be an expensive experience. The highway patrol even carries credit card machines to make sure foreigners pay their speeding ticket on site...
On some particularly nasty road stretches, speed limits are dropped from 80 to 70 km/h in winter. Normal speed limits on the country roads are 80 km/h, but you will encounter long stretches with 60 and 70 km/h. Highways have a max of 90 km/h, while some newer highways close to Oslo have a max of 100 km/h. Max speed within town boundaries is 50 km/h - and it is here where the penalty for speeding is the highest.
Rule of thumb: In 80 zones, it is safe to put your speedometer needle at 100. In 90, max 110, and in 100 zone, max 120. The police give you some slack when they read your speed. But in 50 zones and below they are merciless. More or less.
As for Sweden, I know they have better roads, more 110 km/h zones, and generally is a better place to drive fast(er) - however your trip will not be so scenic. The nice twisty roads are to be found in Norway.
If you're not on route yet, or reads this while in Norway: call me up if you're passing by Oslo.